IB · PHYSICS SL

Physics: Standard Level

The particulate nature of matter — Theme B

Name: ____________________Date: October 10, 2026

1.
A 0.50 kg metal block receives 9000 J of thermal energy and its temperature rises by 40°C. Calculate its specific heat capacity.
[3 marks]
Answer explanation
Draft walkthroughs are based on marking guidance, not independently verified derivations.
1. List the given quantities and the requested unknown. Choose the relation that connects them, state any required assumptions, then substitute before rounding. Preserve exact expressions when the task asks for an exact result.
2. Work through this mathematical step: Uses Q = mcΔT. Write the intermediate operation, keep the units consistent where applicable, and check the relation against the quantities given in the question.
3. Work through this mathematical step: Rearranges to c = Q/(mΔT). Write the intermediate operation, keep the units consistent where applicable, and check the relation against the quantities given in the question.
4. Work through this mathematical step: Substitutes 9000/(0.50 × 40) to obtain c = 450 J kg⁻¹ K⁻¹. Write the intermediate operation, keep the units consistent where applicable, and check the relation against the quantities given in the question.
5. Check the complete task again, including restrictions, units, precision and supporting evidence when relevant. Specific caution: Use the temperature change, not the final temperature, in the specific heat capacity equation.
Marking points
- Uses Q = mcΔT.
- Rearranges to c = Q/(mΔT).
- Substitutes 9000/(0.50 × 40) to obtain c = 450 J kg⁻¹ K⁻¹.
Examiner tip: Use the temperature change, not the final temperature, in the specific heat capacity equation.
2.
Marking analysis: A learner attempts the following task: “A 0.50 kg metal block receives 9000 J of thermal energy and its temperature rises by 40°C. Calculate its specific heat capacity.” Their response addresses only this point: “Uses Q = mcΔT.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[3 marks]
Answer explanation
Draft walkthroughs are based on marking guidance, not independently verified derivations.
1. Separate the learner's stated response from the complete task. Credit only what their response demonstrates, then identify each missing requirement; do not assume unstated working.
2. Requirement 1: Recognises credit for the stated point: Uses Q = mcΔT. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
3. Requirement 2: Identifies the missing requirement: Rearranges to c = Q/(mΔT). Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
4. Requirement 3: Identifies the missing requirement: Substitutes 9000/(0.50 × 40) to obtain c = 450 J kg⁻¹ K⁻¹. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
5. Check the complete task again, including restrictions, units, precision and supporting evidence when relevant. Specific caution: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
Marking points
- Recognises credit for the stated point: Uses Q = mcΔT.
- Identifies the missing requirement: Rearranges to c = Q/(mΔT).
- Identifies the missing requirement: Substitutes 9000/(0.50 × 40) to obtain c = 450 J kg⁻¹ K⁻¹.
Examiner tip: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
3.
A 0.20 kg sample of ice at 0°C absorbs 66 800 J of energy and fully melts. Calculate the specific latent heat of fusion of ice.
[3 marks]
Answer explanation
Draft walkthroughs are based on marking guidance, not independently verified derivations.
1. List the given quantities and the requested unknown. Choose the relation that connects them, state any required assumptions, then substitute before rounding. Preserve exact expressions when the task asks for an exact result.
2. Work through this mathematical step: Uses Q = mL. Write the intermediate operation, keep the units consistent where applicable, and check the relation against the quantities given in the question.
3. Work through this mathematical step: Rearranges to L = Q/m. Write the intermediate operation, keep the units consistent where applicable, and check the relation against the quantities given in the question.
4. Work through this mathematical step: Substitutes 66 800/0.20 to obtain L = 334 000 J kg⁻¹. Write the intermediate operation, keep the units consistent where applicable, and check the relation against the quantities given in the question.
5. Check the complete task again, including restrictions, units, precision and supporting evidence when relevant. Specific caution: During a phase change, temperature stays constant even though energy is being transferred — this is what distinguishes latent heat from specific heat capacity calculations.
Marking points
- Uses Q = mL.
- Rearranges to L = Q/m.
- Substitutes 66 800/0.20 to obtain L = 334 000 J kg⁻¹.
Examiner tip: During a phase change, temperature stays constant even though energy is being transferred — this is what distinguishes latent heat from specific heat capacity calculations.
4.
Marking analysis: A learner attempts the following task: “A 0.20 kg sample of ice at 0°C absorbs 66 800 J of energy and fully melts. Calculate the specific latent heat of fusion of ice.” Their response addresses only this point: “Uses Q = mL.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[3 marks]
Answer explanation
Draft walkthroughs are based on marking guidance, not independently verified derivations.
1. Separate the learner's stated response from the complete task. Credit only what their response demonstrates, then identify each missing requirement; do not assume unstated working.
2. Requirement 1: Recognises credit for the stated point: Uses Q = mL. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
3. Requirement 2: Identifies the missing requirement: Rearranges to L = Q/m. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
4. Requirement 3: Identifies the missing requirement: Substitutes 66 800/0.20 to obtain L = 334 000 J kg⁻¹. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
5. Check the complete task again, including restrictions, units, precision and supporting evidence when relevant. Specific caution: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
Marking points
- Recognises credit for the stated point: Uses Q = mL.
- Identifies the missing requirement: Rearranges to L = Q/m.
- Identifies the missing requirement: Substitutes 66 800/0.20 to obtain L = 334 000 J kg⁻¹.
Examiner tip: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
5.
Explain, using the kinetic particle model, why the pressure of a fixed mass of gas increases when it is heated at constant volume.
[3 marks] · no calculator
Answer explanation
Draft walkthroughs are based on marking guidance, not independently verified derivations.
1. Break the command into its requested parts. For each part, connect a relevant fact or observation to the conclusion it supports. Describing what happens and explaining why it happens are different tasks.
2. Develop this part of the answer: States that heating increases the average kinetic energy (speed) of the gas particles. Show which detail or principle supports it and how it addresses the command; equivalent supported wording is acceptable.
3. Develop this part of the answer: States that faster particles collide with the container walls more frequently. Show which detail or principle supports it and how it addresses the command; equivalent supported wording is acceptable.
4. Develop this part of the answer: States that faster particles also transfer greater force (momentum change) per collision, so both effects increase the pressure exerted on the walls. Show which detail or principle supports it and how it addresses the command; equivalent supported wording is acceptable.
5. Check the complete task again, including restrictions, units, precision and supporting evidence when relevant. Specific caution: A complete kinetic-model explanation mentions both increased collision frequency and increased force per collision, not just one.
Marking points
- States that heating increases the average kinetic energy (speed) of the gas particles.
- States that faster particles collide with the container walls more frequently.
- States that faster particles also transfer greater force (momentum change) per collision, so both effects increase the pressure exerted on the walls.
Examiner tip: A complete kinetic-model explanation mentions both increased collision frequency and increased force per collision, not just one.
6.
Marking analysis: A learner attempts the following task: “Explain, using the kinetic particle model, why the pressure of a fixed mass of gas increases when it is heated at constant volume.” Their response addresses only this point: “States that heating increases the average kinetic energy (speed) of the gas particles.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[3 marks] · no calculator
Answer explanation
Draft walkthroughs are based on marking guidance, not independently verified derivations.
1. Separate the learner's stated response from the complete task. Credit only what their response demonstrates, then identify each missing requirement; do not assume unstated working.
2. Requirement 1: Recognises credit for the stated point: States that heating increases the average kinetic energy (speed) of the gas particles. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
3. Requirement 2: Identifies the missing requirement: States that faster particles collide with the container walls more frequently. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
4. Requirement 3: Identifies the missing requirement: States that faster particles also transfer greater force (momentum change) per collision, so both effects increase the pressure exerted on the walls. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
5. Check the complete task again, including restrictions, units, precision and supporting evidence when relevant. Specific caution: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
Marking points
- Recognises credit for the stated point: States that heating increases the average kinetic energy (speed) of the gas particles.
- Identifies the missing requirement: States that faster particles collide with the container walls more frequently.
- Identifies the missing requirement: States that faster particles also transfer greater force (momentum change) per collision, so both effects increase the pressure exerted on the walls.
Examiner tip: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
7.
A fixed mass of gas occupies 2.0 m³ at a pressure of 1.0 × 10⁵ Pa. It is compressed at constant temperature to a volume of 0.50 m³. Calculate the new pressure.
[3 marks]
Answer explanation
Draft walkthroughs are based on marking guidance, not independently verified derivations.
1. List the given quantities and the requested unknown. Choose the relation that connects them, state any required assumptions, then substitute before rounding. Preserve exact expressions when the task asks for an exact result.
2. Work through this mathematical step: States Boyle's law: p₁V₁ = p₂V₂ for constant temperature. Write the intermediate operation, keep the units consistent where applicable, and check the relation against the quantities given in the question.
3. Work through this mathematical step: Substitutes (1.0 × 10⁵)(2.0) = p₂(0.50). Write the intermediate operation, keep the units consistent where applicable, and check the relation against the quantities given in the question.
4. Work through this mathematical step: Obtains p₂ = 4.0 × 10⁵ Pa. Write the intermediate operation, keep the units consistent where applicable, and check the relation against the quantities given in the question.
5. Check the complete task again, including restrictions, units, precision and supporting evidence when relevant. Specific caution: Boyle's law only applies at constant temperature and for a fixed mass of gas — check both conditions hold before applying it.
Marking points
- States Boyle's law: p₁V₁ = p₂V₂ for constant temperature.
- Substitutes (1.0 × 10⁵)(2.0) = p₂(0.50).
- Obtains p₂ = 4.0 × 10⁵ Pa.
Examiner tip: Boyle's law only applies at constant temperature and for a fixed mass of gas — check both conditions hold before applying it.
8.
Marking analysis: A learner attempts the following task: “A fixed mass of gas occupies 2.0 m³ at a pressure of 1.0 × 10⁵ Pa. It is compressed at constant temperature to a volume of 0.50 m³. Calculate the new pressure.” Their response addresses only this point: “States Boyle's law: p₁V₁ = p₂V₂ for constant temperature.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[3 marks]
Answer explanation
Draft walkthroughs are based on marking guidance, not independently verified derivations.
1. Separate the learner's stated response from the complete task. Credit only what their response demonstrates, then identify each missing requirement; do not assume unstated working.
2. Requirement 1: Recognises credit for the stated point: States Boyle's law: p₁V₁ = p₂V₂ for constant temperature. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
3. Requirement 2: Identifies the missing requirement: Substitutes (1.0 × 10⁵)(2.0) = p₂(0.50). Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
4. Requirement 3: Identifies the missing requirement: Obtains p₂ = 4.0 × 10⁵ Pa. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
5. Check the complete task again, including restrictions, units, precision and supporting evidence when relevant. Specific caution: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
Marking points
- Recognises credit for the stated point: States Boyle's law: p₁V₁ = p₂V₂ for constant temperature.
- Identifies the missing requirement: Substitutes (1.0 × 10⁵)(2.0) = p₂(0.50).
- Identifies the missing requirement: Obtains p₂ = 4.0 × 10⁵ Pa.
Examiner tip: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
9.
A current of 3.0 A flows through a resistor for 5 minutes. Calculate the charge that flows and, given the resistor has resistance 4.0 Ω, the power dissipated.
[4 marks]
Answer explanation
Draft walkthroughs are based on marking guidance, not independently verified derivations.
1. List the given quantities and the requested unknown. Choose the relation that connects them, state any required assumptions, then substitute before rounding. Preserve exact expressions when the task asks for an exact result.
2. Work through this mathematical step: Converts time to seconds: 5 × 60 = 300 s. Write the intermediate operation, keep the units consistent where applicable, and check the relation against the quantities given in the question.
3. Work through this mathematical step: Uses charge Q = It to obtain Q = 900 C. Write the intermediate operation, keep the units consistent where applicable, and check the relation against the quantities given in the question.
4. Work through this mathematical step: Uses power P = I²R. Write the intermediate operation, keep the units consistent where applicable, and check the relation against the quantities given in the question.
5. Work through this mathematical step: Substitutes 3.0² × 4.0 to obtain P = 36 W. Write the intermediate operation, keep the units consistent where applicable, and check the relation against the quantities given in the question.
6. Check the complete task again, including restrictions, units, precision and supporting evidence when relevant. Specific caution: Always convert time to seconds before using Q = It, since current is defined in coulombs per second.
Marking points
- Converts time to seconds: 5 × 60 = 300 s.
- Uses charge Q = It to obtain Q = 900 C.
- Uses power P = I²R.
- Substitutes 3.0² × 4.0 to obtain P = 36 W.
Examiner tip: Always convert time to seconds before using Q = It, since current is defined in coulombs per second.
10.
Marking analysis: A learner attempts the following task: “A current of 3.0 A flows through a resistor for 5 minutes. Calculate the charge that flows and, given the resistor has resistance 4.0 Ω, the power dissipated.” Their response addresses only this point: “Converts time to seconds: 5 × 60 = 300 s.” Evaluate the response against the complete 4-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[4 marks]
Answer explanation
Draft walkthroughs are based on marking guidance, not independently verified derivations.
1. Separate the learner's stated response from the complete task. Credit only what their response demonstrates, then identify each missing requirement; do not assume unstated working.
2. Requirement 1: Recognises credit for the stated point: Converts time to seconds: 5 × 60 = 300 s. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
3. Requirement 2: Identifies the missing requirement: Uses charge Q = It to obtain Q = 900 C. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
4. Requirement 3: Identifies the missing requirement: Uses power P = I²R. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
5. Requirement 4: Identifies the missing requirement: Substitutes 3.0² × 4.0 to obtain P = 36 W. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
6. Check the complete task again, including restrictions, units, precision and supporting evidence when relevant. Specific caution: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
Marking points
- Recognises credit for the stated point: Converts time to seconds: 5 × 60 = 300 s.
- Identifies the missing requirement: Uses charge Q = It to obtain Q = 900 C.
- Identifies the missing requirement: Uses power P = I²R.
- Identifies the missing requirement: Substitutes 3.0² × 4.0 to obtain P = 36 W.
Examiner tip: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
11.
Three 4.0 Ω resistors are connected in series with a 24 V battery. Calculate the current flowing and the voltage across each resistor.
[4 marks]
Answer explanation
Draft walkthroughs are based on marking guidance, not independently verified derivations.
1. List the given quantities and the requested unknown. Choose the relation that connects them, state any required assumptions, then substitute before rounding. Preserve exact expressions when the task asks for an exact result.
2. Work through this mathematical step: Calculates total resistance for series resistors: 4.0 + 4.0 + 4.0 = 12.0 Ω. Write the intermediate operation, keep the units consistent where applicable, and check the relation against the quantities given in the question.
3. Work through this mathematical step: Uses I = V/R = 24/12.0. Write the intermediate operation, keep the units consistent where applicable, and check the relation against the quantities given in the question.
4. Work through this mathematical step: Obtains current = 2.0 A. Write the intermediate operation, keep the units consistent where applicable, and check the relation against the quantities given in the question.
5. Work through this mathematical step: Uses V = IR = 2.0 × 4.0 to obtain 8.0 V across each resistor. Write the intermediate operation, keep the units consistent where applicable, and check the relation against the quantities given in the question.
6. Check the complete task again, including restrictions, units, precision and supporting evidence when relevant. Specific caution: In a series circuit, resistances simply add; the current stays the same throughout, and the voltage divides between resistors in proportion to their resistance.
Marking points
- Calculates total resistance for series resistors: 4.0 + 4.0 + 4.0 = 12.0 Ω.
- Uses I = V/R = 24/12.0.
- Obtains current = 2.0 A.
- Uses V = IR = 2.0 × 4.0 to obtain 8.0 V across each resistor.
Examiner tip: In a series circuit, resistances simply add; the current stays the same throughout, and the voltage divides between resistors in proportion to their resistance.
12.
Marking analysis: A learner attempts the following task: “Three 4.0 Ω resistors are connected in series with a 24 V battery. Calculate the current flowing and the voltage across each resistor.” Their response addresses only this point: “Calculates total resistance for series resistors: 4.0 + 4.0 + 4.0 = 12.0 Ω.” Evaluate the response against the complete 4-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[4 marks]
Answer explanation
Draft walkthroughs are based on marking guidance, not independently verified derivations.
1. Separate the learner's stated response from the complete task. Credit only what their response demonstrates, then identify each missing requirement; do not assume unstated working.
2. Requirement 1: Recognises credit for the stated point: Calculates total resistance for series resistors: 4.0 + 4.0 + 4.0 = 12.0 Ω. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
3. Requirement 2: Identifies the missing requirement: Uses I = V/R = 24/12.0. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
4. Requirement 3: Identifies the missing requirement: Obtains current = 2.0 A. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
5. Requirement 4: Identifies the missing requirement: Uses V = IR = 2.0 × 4.0 to obtain 8.0 V across each resistor. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
6. Check the complete task again, including restrictions, units, precision and supporting evidence when relevant. Specific caution: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
Marking points
- Recognises credit for the stated point: Calculates total resistance for series resistors: 4.0 + 4.0 + 4.0 = 12.0 Ω.
- Identifies the missing requirement: Uses I = V/R = 24/12.0.
- Identifies the missing requirement: Obtains current = 2.0 A.
- Identifies the missing requirement: Uses V = IR = 2.0 × 4.0 to obtain 8.0 V across each resistor.
Examiner tip: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
13.
Two 6.0 Ω resistors are connected in parallel. Calculate their combined resistance.
[2 marks]
Answer explanation
Draft walkthroughs are based on marking guidance, not independently verified derivations.
1. List the given quantities and the requested unknown. Choose the relation that connects them, state any required assumptions, then substitute before rounding. Preserve exact expressions when the task asks for an exact result.
2. Work through this mathematical step: Uses 1/R = 1/6.0 + 1/6.0. Write the intermediate operation, keep the units consistent where applicable, and check the relation against the quantities given in the question.
3. Work through this mathematical step: Obtains R = 3.0 Ω. Write the intermediate operation, keep the units consistent where applicable, and check the relation against the quantities given in the question.
4. Check the complete task again, including restrictions, units, precision and supporting evidence when relevant. Specific caution: A parallel combination always has a total resistance smaller than the smallest individual resistor.
Marking points
- Uses 1/R = 1/6.0 + 1/6.0.
- Obtains R = 3.0 Ω.
Examiner tip: A parallel combination always has a total resistance smaller than the smallest individual resistor.
14.
Marking analysis: A learner attempts the following task: “Two 6.0 Ω resistors are connected in parallel. Calculate their combined resistance.” Their response addresses only this point: “Uses 1/R = 1/6.0 + 1/6.0.” Evaluate the response against the complete 2-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[2 marks]
Answer explanation
Draft walkthroughs are based on marking guidance, not independently verified derivations.
1. Separate the learner's stated response from the complete task. Credit only what their response demonstrates, then identify each missing requirement; do not assume unstated working.
2. Requirement 1: Recognises credit for the stated point: Uses 1/R = 1/6.0 + 1/6.0. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
3. Requirement 2: Identifies the missing requirement: Obtains R = 3.0 Ω. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
4. Check the complete task again, including restrictions, units, precision and supporting evidence when relevant. Specific caution: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
Marking points
- Recognises credit for the stated point: Uses 1/R = 1/6.0 + 1/6.0.
- Identifies the missing requirement: Obtains R = 3.0 Ω.
Examiner tip: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
15.
Describe, in terms of particle arrangement and movement, the difference between a liquid and a gas.
[3 marks] · no calculator
Answer explanation
Draft walkthroughs are based on marking guidance, not independently verified derivations.
1. Break the command into its requested parts. For each part, connect a relevant fact or observation to the conclusion it supports. Describing what happens and explaining why it happens are different tasks.
2. Develop this part of the answer: States that in a liquid, particles are close together with weak intermolecular forces, able to move past one another but not separate far. Show which detail or principle supports it and how it addresses the command; equivalent supported wording is acceptable.
3. Develop this part of the answer: States that in a gas, particles are far apart with negligible intermolecular forces, moving freely and randomly at high speed. Show which detail or principle supports it and how it addresses the command; equivalent supported wording is acceptable.
4. Develop this part of the answer: States that this difference explains why a gas can be easily compressed while a liquid cannot. Show which detail or principle supports it and how it addresses the command; equivalent supported wording is acceptable.
5. Check the complete task again, including restrictions, units, precision and supporting evidence when relevant. Specific caution: Always describe both particle spacing/arrangement and movement for full marks in kinetic particle theory questions.
Marking points
- States that in a liquid, particles are close together with weak intermolecular forces, able to move past one another but not separate far.
- States that in a gas, particles are far apart with negligible intermolecular forces, moving freely and randomly at high speed.
- States that this difference explains why a gas can be easily compressed while a liquid cannot.
Examiner tip: Always describe both particle spacing/arrangement and movement for full marks in kinetic particle theory questions.
16.
Marking analysis: A learner attempts the following task: “Describe, in terms of particle arrangement and movement, the difference between a liquid and a gas.” Their response addresses only this point: “States that in a liquid, particles are close together with weak intermolecular forces, able to move past one another but not separate far.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[3 marks] · no calculator
Answer explanation
Draft walkthroughs are based on marking guidance, not independently verified derivations.
1. Separate the learner's stated response from the complete task. Credit only what their response demonstrates, then identify each missing requirement; do not assume unstated working.
2. Requirement 1: Recognises credit for the stated point: States that in a liquid, particles are close together with weak intermolecular forces, able to move past one another but not separate far. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
3. Requirement 2: Identifies the missing requirement: States that in a gas, particles are far apart with negligible intermolecular forces, moving freely and randomly at high speed. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
4. Requirement 3: Identifies the missing requirement: States that this difference explains why a gas can be easily compressed while a liquid cannot. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
5. Check the complete task again, including restrictions, units, precision and supporting evidence when relevant. Specific caution: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
Marking points
- Recognises credit for the stated point: States that in a liquid, particles are close together with weak intermolecular forces, able to move past one another but not separate far.
- Identifies the missing requirement: States that in a gas, particles are far apart with negligible intermolecular forces, moving freely and randomly at high speed.
- Identifies the missing requirement: States that this difference explains why a gas can be easily compressed while a liquid cannot.
Examiner tip: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
17.
A resistor of resistance R dissipates power P when connected to a fixed voltage V. Explain what happens to the power dissipated if the resistance is doubled, with V unchanged.
[3 marks] · no calculator
Answer explanation
Draft walkthroughs are based on marking guidance, not independently verified derivations.
1. Break the command into its requested parts. For each part, connect a relevant fact or observation to the conclusion it supports. Describing what happens and explaining why it happens are different tasks.
2. Work through this mathematical step: States the relation P = V²/R for power in terms of fixed voltage and resistance. Write the intermediate operation, keep the units consistent where applicable, and check the relation against the quantities given in the question.
3. Develop this part of the answer: States that since V is fixed, power is inversely proportional to resistance. Show which detail or principle supports it and how it addresses the command; equivalent supported wording is acceptable.
4. Develop this part of the answer: States that doubling R halves the power dissipated. Show which detail or principle supports it and how it addresses the command; equivalent supported wording is acceptable.
5. Check the complete task again, including restrictions, units, precision and supporting evidence when relevant. Specific caution: Choose the power formula (P=IV, P=I²R, or P=V²/R) that matches which quantity is held fixed in the scenario — here V is fixed, so P=V²/R is most direct.
Marking points
- States the relation P = V²/R for power in terms of fixed voltage and resistance.
- States that since V is fixed, power is inversely proportional to resistance.
- States that doubling R halves the power dissipated.
Examiner tip: Choose the power formula (P=IV, P=I²R, or P=V²/R) that matches which quantity is held fixed in the scenario — here V is fixed, so P=V²/R is most direct.
18.
Marking analysis: A learner attempts the following task: “A resistor of resistance R dissipates power P when connected to a fixed voltage V. Explain what happens to the power dissipated if the resistance is doubled, with V unchanged.” Their response addresses only this point: “States the relation P = V²/R for power in terms of fixed voltage and resistance.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[3 marks] · no calculator
Answer explanation
Draft walkthroughs are based on marking guidance, not independently verified derivations.
1. Separate the learner's stated response from the complete task. Credit only what their response demonstrates, then identify each missing requirement; do not assume unstated working.
2. Requirement 1: Recognises credit for the stated point: States the relation P = V²/R for power in terms of fixed voltage and resistance. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
3. Requirement 2: Identifies the missing requirement: States that since V is fixed, power is inversely proportional to resistance. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
4. Requirement 3: Identifies the missing requirement: States that doubling R halves the power dissipated. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
5. Check the complete task again, including restrictions, units, precision and supporting evidence when relevant. Specific caution: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
Marking points
- Recognises credit for the stated point: States the relation P = V²/R for power in terms of fixed voltage and resistance.
- Identifies the missing requirement: States that since V is fixed, power is inversely proportional to resistance.
- Identifies the missing requirement: States that doubling R halves the power dissipated.
Examiner tip: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
19.
A gas at temperature 27°C and pressure 1.0 × 10⁵ Pa occupies a volume of 0.020 m³ in a sealed rigid container. It is heated to 127°C. Calculate the new pressure, assuming the volume is constant.
[4 marks]
Answer explanation
Draft walkthroughs are based on marking guidance, not independently verified derivations.
1. List the given quantities and the requested unknown. Choose the relation that connects them, state any required assumptions, then substitute before rounding. Preserve exact expressions when the task asks for an exact result.
2. Work through this mathematical step: Converts both temperatures to kelvin: 27°C = 300 K, 127°C = 400 K. Write the intermediate operation, keep the units consistent where applicable, and check the relation against the quantities given in the question.
3. Work through this mathematical step: States the pressure law at constant volume: p₁/T₁ = p₂/T₂. Write the intermediate operation, keep the units consistent where applicable, and check the relation against the quantities given in the question.
4. Work through this mathematical step: Substitutes (1.0 × 10⁵)/300 = p₂/400. Write the intermediate operation, keep the units consistent where applicable, and check the relation against the quantities given in the question.
5. Develop this part of the answer: Obtains p₂ ≈ 1.33 × 10⁵ Pa. Show which detail or principle supports it and how it addresses the command; equivalent supported wording is acceptable.
6. Check the complete task again, including restrictions, units, precision and supporting evidence when relevant. Specific caution: Gas law equations always require absolute temperature in kelvin, never Celsius — converting is the most common step students forget.
Marking points
- Converts both temperatures to kelvin: 27°C = 300 K, 127°C = 400 K.
- States the pressure law at constant volume: p₁/T₁ = p₂/T₂.
- Substitutes (1.0 × 10⁵)/300 = p₂/400.
- Obtains p₂ ≈ 1.33 × 10⁵ Pa.
Examiner tip: Gas law equations always require absolute temperature in kelvin, never Celsius — converting is the most common step students forget.
20.
Marking analysis: A learner attempts the following task: “A gas at temperature 27°C and pressure 1.0 × 10⁵ Pa occupies a volume of 0.020 m³ in a sealed rigid container. It is heated to 127°C. Calculate the new pressure, assuming the volume is constant.” Their response addresses only this point: “Converts both temperatures to kelvin: 27°C = 300 K, 127°C = 400 K.” Evaluate the response against the complete 4-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[4 marks]
Answer explanation
Draft walkthroughs are based on marking guidance, not independently verified derivations.
1. Separate the learner's stated response from the complete task. Credit only what their response demonstrates, then identify each missing requirement; do not assume unstated working.
2. Requirement 1: Recognises credit for the stated point: Converts both temperatures to kelvin: 27°C = 300 K, 127°C = 400 K. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
3. Requirement 2: Identifies the missing requirement: States the pressure law at constant volume: p₁/T₁ = p₂/T₂. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
4. Requirement 3: Identifies the missing requirement: Substitutes (1.0 × 10⁵)/300 = p₂/400. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
5. Requirement 4: Identifies the missing requirement: Obtains p₂ ≈ 1.33 × 10⁵ Pa. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
6. Check the complete task again, including restrictions, units, precision and supporting evidence when relevant. Specific caution: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
Marking points
- Recognises credit for the stated point: Converts both temperatures to kelvin: 27°C = 300 K, 127°C = 400 K.
- Identifies the missing requirement: States the pressure law at constant volume: p₁/T₁ = p₂/T₂.
- Identifies the missing requirement: Substitutes (1.0 × 10⁵)/300 = p₂/400.
- Identifies the missing requirement: Obtains p₂ ≈ 1.33 × 10⁵ Pa.
Examiner tip: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
21.
Calculate the number of moles of an ideal gas that occupies a volume of 0.0500 m³ at a pressure of 2.0 × 10⁵ Pa and a temperature of 300 K. Use R = 8.31 J K⁻¹ mol⁻¹.
[4 marks]
Answer explanation
Draft walkthroughs are based on marking guidance, not independently verified derivations.
1. List the given quantities and the requested unknown. Choose the relation that connects them, state any required assumptions, then substitute before rounding. Preserve exact expressions when the task asks for an exact result.
2. Work through this mathematical step: States the ideal gas equation: PV = nRT. Write the intermediate operation, keep the units consistent where applicable, and check the relation against the quantities given in the question.
3. Work through this mathematical step: Rearranges to n = PV/RT. Write the intermediate operation, keep the units consistent where applicable, and check the relation against the quantities given in the question.
4. Work through this mathematical step: Substitutes n = (2.0 × 10⁵ × 0.0500)/(8.31 × 300). Write the intermediate operation, keep the units consistent where applicable, and check the relation against the quantities given in the question.
5. Develop this part of the answer: Obtains n ≈ 4.01 mol. Show which detail or principle supports it and how it addresses the command; equivalent supported wording is acceptable.
6. Check the complete task again, including restrictions, units, precision and supporting evidence when relevant. Specific caution: The ideal gas equation combines Boyle's law, the pressure law and Charles's law into a single relationship — it should be used directly whenever moles or R are involved, rather than combining the separate gas laws.
Marking points
- States the ideal gas equation: PV = nRT.
- Rearranges to n = PV/RT.
- Substitutes n = (2.0 × 10⁵ × 0.0500)/(8.31 × 300).
- Obtains n ≈ 4.01 mol.
Examiner tip: The ideal gas equation combines Boyle's law, the pressure law and Charles's law into a single relationship — it should be used directly whenever moles or R are involved, rather than combining the separate gas laws.
22.
Marking analysis: A learner attempts the following task: “Calculate the number of moles of an ideal gas that occupies a volume of 0.0500 m³ at a pressure of 2.0 × 10⁵ Pa and a temperature of 300 K. Use R = 8.31 J K⁻¹ mol⁻¹.” Their response addresses only this point: “States the ideal gas equation: PV = nRT.” Evaluate the response against the complete 4-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[4 marks]
Answer explanation
Draft walkthroughs are based on marking guidance, not independently verified derivations.
1. Separate the learner's stated response from the complete task. Credit only what their response demonstrates, then identify each missing requirement; do not assume unstated working.
2. Requirement 1: Recognises credit for the stated point: States the ideal gas equation: PV = nRT. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
3. Requirement 2: Identifies the missing requirement: Rearranges to n = PV/RT. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
4. Requirement 3: Identifies the missing requirement: Substitutes n = (2.0 × 10⁵ × 0.0500)/(8.31 × 300). Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
5. Requirement 4: Identifies the missing requirement: Obtains n ≈ 4.01 mol. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
6. Check the complete task again, including restrictions, units, precision and supporting evidence when relevant. Specific caution: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
Marking points
- Recognises credit for the stated point: States the ideal gas equation: PV = nRT.
- Identifies the missing requirement: Rearranges to n = PV/RT.
- Identifies the missing requirement: Substitutes n = (2.0 × 10⁵ × 0.0500)/(8.31 × 300).
- Identifies the missing requirement: Obtains n ≈ 4.01 mol.
Examiner tip: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
23.
A battery of EMF 12 V and internal resistance 0.50 Ω is connected to an external resistor of 5.5 Ω. Calculate the current in the circuit and the terminal voltage of the battery.
[5 marks]
Answer explanation
Draft walkthroughs are based on marking guidance, not independently verified derivations.
1. List the given quantities and the requested unknown. Choose the relation that connects them, state any required assumptions, then substitute before rounding. Preserve exact expressions when the task asks for an exact result.
2. Work through this mathematical step: States EMF = I(R + r), where R is the external resistance and r is the internal resistance. Write the intermediate operation, keep the units consistent where applicable, and check the relation against the quantities given in the question.
3. Work through this mathematical step: Substitutes 12 = I(5.5 + 0.50). Write the intermediate operation, keep the units consistent where applicable, and check the relation against the quantities given in the question.
4. Work through this mathematical step: Obtains I = 12/6.0 = 2.0 A. Write the intermediate operation, keep the units consistent where applicable, and check the relation against the quantities given in the question.
5. Work through this mathematical step: Uses terminal voltage = EMF − Ir. Write the intermediate operation, keep the units consistent where applicable, and check the relation against the quantities given in the question.
6. Work through this mathematical step: Obtains terminal voltage = 12 − (2.0 × 0.50) = 11.0 V. Write the intermediate operation, keep the units consistent where applicable, and check the relation against the quantities given in the question.
7. Check the complete task again, including restrictions, units, precision and supporting evidence when relevant. Specific caution: The terminal voltage is always less than the EMF whenever current flows, since some voltage is inevitably 'lost' driving current through the battery's own internal resistance.
Marking points
- States EMF = I(R + r), where R is the external resistance and r is the internal resistance.
- Substitutes 12 = I(5.5 + 0.50).
- Obtains I = 12/6.0 = 2.0 A.
- Uses terminal voltage = EMF − Ir.
- Obtains terminal voltage = 12 − (2.0 × 0.50) = 11.0 V.
Examiner tip: The terminal voltage is always less than the EMF whenever current flows, since some voltage is inevitably 'lost' driving current through the battery's own internal resistance.
24.
Marking analysis: A learner attempts the following task: “A battery of EMF 12 V and internal resistance 0.50 Ω is connected to an external resistor of 5.5 Ω. Calculate the current in the circuit and the terminal voltage of the battery.” Their response addresses only this point: “States EMF = I(R + r), where R is the external resistance and r is the internal resistance.” Evaluate the response against the complete 5-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[5 marks]
Answer explanation
Draft walkthroughs are based on marking guidance, not independently verified derivations.
1. Separate the learner's stated response from the complete task. Credit only what their response demonstrates, then identify each missing requirement; do not assume unstated working.
2. Requirement 1: Recognises credit for the stated point: States EMF = I(R + r), where R is the external resistance and r is the internal resistance. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
3. Requirement 2: Identifies the missing requirement: Substitutes 12 = I(5.5 + 0.50). Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
4. Requirement 3: Identifies the missing requirement: Obtains I = 12/6.0 = 2.0 A. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
5. Requirement 4: Identifies the missing requirement: Uses terminal voltage = EMF − Ir. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
6. Requirement 5: Identifies the missing requirement: Obtains terminal voltage = 12 − (2.0 × 0.50) = 11.0 V. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
7. Check the complete task again, including restrictions, units, precision and supporting evidence when relevant. Specific caution: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
Marking points
- Recognises credit for the stated point: States EMF = I(R + r), where R is the external resistance and r is the internal resistance.
- Identifies the missing requirement: Substitutes 12 = I(5.5 + 0.50).
- Identifies the missing requirement: Obtains I = 12/6.0 = 2.0 A.
- Identifies the missing requirement: Uses terminal voltage = EMF − Ir.
- Identifies the missing requirement: Obtains terminal voltage = 12 − (2.0 × 0.50) = 11.0 V.
Examiner tip: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
25.
A potential divider circuit consists of two resistors, 20 Ω and 30 Ω, connected in series across a 10 V supply. Calculate the potential difference across the 30 Ω resistor.
[3 marks]
Answer explanation
Draft walkthroughs are based on marking guidance, not independently verified derivations.
1. List the given quantities and the requested unknown. Choose the relation that connects them, state any required assumptions, then substitute before rounding. Preserve exact expressions when the task asks for an exact result.
2. Work through this mathematical step: Uses the potential divider formula: V_out = V_in × (R₂/(R₁ + R₂)), taking R₂ as the resistor of interest. Write the intermediate operation, keep the units consistent where applicable, and check the relation against the quantities given in the question.
3. Work through this mathematical step: Substitutes 10 × (30/(20 + 30)). Write the intermediate operation, keep the units consistent where applicable, and check the relation against the quantities given in the question.
4. Work through this mathematical step: Obtains V = 6.0 V. Write the intermediate operation, keep the units consistent where applicable, and check the relation against the quantities given in the question.
5. Check the complete task again, including restrictions, units, precision and supporting evidence when relevant. Specific caution: In a potential divider, voltage splits between series resistors in direct proportion to their resistance — the larger resistor always gets the larger share of the supply voltage.
Marking points
- Uses the potential divider formula: V_out = V_in × (R₂/(R₁ + R₂)), taking R₂ as the resistor of interest.
- Substitutes 10 × (30/(20 + 30)).
- Obtains V = 6.0 V.
Examiner tip: In a potential divider, voltage splits between series resistors in direct proportion to their resistance — the larger resistor always gets the larger share of the supply voltage.
26.
Marking analysis: A learner attempts the following task: “A potential divider circuit consists of two resistors, 20 Ω and 30 Ω, connected in series across a 10 V supply. Calculate the potential difference across the 30 Ω resistor.” Their response addresses only this point: “Uses the potential divider formula: V_out = V_in × (R₂/(R₁ + R₂)), taking R₂ as the resistor of interest.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[3 marks]
Answer explanation
Draft walkthroughs are based on marking guidance, not independently verified derivations.
1. Separate the learner's stated response from the complete task. Credit only what their response demonstrates, then identify each missing requirement; do not assume unstated working.
2. Requirement 1: Recognises credit for the stated point: Uses the potential divider formula: V_out = V_in × (R₂/(R₁ + R₂)), taking R₂ as the resistor of interest. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
3. Requirement 2: Identifies the missing requirement: Substitutes 10 × (30/(20 + 30)). Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
4. Requirement 3: Identifies the missing requirement: Obtains V = 6.0 V. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
5. Check the complete task again, including restrictions, units, precision and supporting evidence when relevant. Specific caution: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
Marking points
- Recognises credit for the stated point: Uses the potential divider formula: V_out = V_in × (R₂/(R₁ + R₂)), taking R₂ as the resistor of interest.
- Identifies the missing requirement: Substitutes 10 × (30/(20 + 30)).
- Identifies the missing requirement: Obtains V = 6.0 V.
Examiner tip: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
27.
State what is meant by absolute zero, and describe what happens to the motion of gas particles as temperature approaches absolute zero.
[2 marks] · no calculator
Answer explanation
Draft walkthroughs are based on marking guidance, not independently verified derivations.
1. Break the command into its requested parts. For each part, connect a relevant fact or observation to the conclusion it supports. Describing what happens and explaining why it happens are different tasks.
2. Develop this part of the answer: States that absolute zero (0 K, −273°C) is the theoretical temperature at which a substance has minimum internal (kinetic) energy. Show which detail or principle supports it and how it addresses the command; equivalent supported wording is acceptable.
3. Develop this part of the answer: States that as temperature approaches absolute zero, the average kinetic energy (speed) of gas particles approaches a minimum, theoretically approaching zero. Show which detail or principle supports it and how it addresses the command; equivalent supported wording is acceptable.
4. Check the complete task again, including restrictions, units, precision and supporting evidence when relevant. Specific caution: The kelvin temperature scale is defined so that 0 K corresponds exactly to absolute zero — this is why gas law equations must always use kelvin rather than Celsius.
Marking points
- States that absolute zero (0 K, −273°C) is the theoretical temperature at which a substance has minimum internal (kinetic) energy.
- States that as temperature approaches absolute zero, the average kinetic energy (speed) of gas particles approaches a minimum, theoretically approaching zero.
Examiner tip: The kelvin temperature scale is defined so that 0 K corresponds exactly to absolute zero — this is why gas law equations must always use kelvin rather than Celsius.
28.
Marking analysis: A learner attempts the following task: “State what is meant by absolute zero, and describe what happens to the motion of gas particles as temperature approaches absolute zero.” Their response addresses only this point: “States that absolute zero (0 K, −273°C) is the theoretical temperature at which a substance has minimum internal (kinetic) energy.” Evaluate the response against the complete 2-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[2 marks] · no calculator
Answer explanation
Draft walkthroughs are based on marking guidance, not independently verified derivations.
1. Separate the learner's stated response from the complete task. Credit only what their response demonstrates, then identify each missing requirement; do not assume unstated working.
2. Requirement 1: Recognises credit for the stated point: States that absolute zero (0 K, −273°C) is the theoretical temperature at which a substance has minimum internal (kinetic) energy. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
3. Requirement 2: Identifies the missing requirement: States that as temperature approaches absolute zero, the average kinetic energy (speed) of gas particles approaches a minimum, theoretically approaching zero. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
4. Check the complete task again, including restrictions, units, precision and supporting evidence when relevant. Specific caution: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
Marking points
- Recognises credit for the stated point: States that absolute zero (0 K, −273°C) is the theoretical temperature at which a substance has minimum internal (kinetic) energy.
- Identifies the missing requirement: States that as temperature approaches absolute zero, the average kinetic energy (speed) of gas particles approaches a minimum, theoretically approaching zero.
Examiner tip: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
29.
Describe an experiment to determine the specific heat capacity of a metal block using an electrical heater, stating the measurements needed and the equation used to calculate the result.
[5 marks] · no calculator
Answer explanation
Draft walkthroughs are based on marking guidance, not independently verified derivations.
1. Break the command into its requested parts. For each part, connect a relevant fact or observation to the conclusion it supports. Describing what happens and explaining why it happens are different tasks.
2. Develop this part of the answer: States that an electrical heater is inserted into a hole in the metal block, with a thermometer used to measure the initial temperature. Show which detail or principle supports it and how it addresses the command; equivalent supported wording is acceptable.
3. Work through this mathematical step: States that the heater is switched on for a measured time, with the current and potential difference recorded to calculate the electrical energy supplied, E = IVt. Write the intermediate operation, keep the units consistent where applicable, and check the relation against the quantities given in the question.
4. Develop this part of the answer: States that the final temperature of the block is recorded, so the temperature rise can be found. Show which detail or principle supports it and how it addresses the command; equivalent supported wording is acceptable.
5. Work through this mathematical step: States that specific heat capacity is calculated using c = E/(mΔT), where m is the mass of the block. Write the intermediate operation, keep the units consistent where applicable, and check the relation against the quantities given in the question.
6. Develop this part of the answer: States that insulating the block reduces heat loss to the surroundings during the experiment, improving the accuracy of the result. Show which detail or principle supports it and how it addresses the command; equivalent supported wording is acceptable.
7. Check the complete task again, including restrictions, units, precision and supporting evidence when relevant. Specific caution: Without insulation, some of the electrical energy supplied is lost to the surroundings rather than heating the block, which would make the calculated specific heat capacity too high.
Marking points
- States that an electrical heater is inserted into a hole in the metal block, with a thermometer used to measure the initial temperature.
- States that the heater is switched on for a measured time, with the current and potential difference recorded to calculate the electrical energy supplied, E = IVt.
- States that the final temperature of the block is recorded, so the temperature rise can be found.
- States that specific heat capacity is calculated using c = E/(mΔT), where m is the mass of the block.
- States that insulating the block reduces heat loss to the surroundings during the experiment, improving the accuracy of the result.
Examiner tip: Without insulation, some of the electrical energy supplied is lost to the surroundings rather than heating the block, which would make the calculated specific heat capacity too high.
30.
Marking analysis: A learner attempts the following task: “Describe an experiment to determine the specific heat capacity of a metal block using an electrical heater, stating the measurements needed and the equation used to calculate the result.” Their response addresses only this point: “States that an electrical heater is inserted into a hole in the metal block, with a thermometer used to measure the initial temperature.” Evaluate the response against the complete 5-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[5 marks] · no calculator
Answer explanation
Draft walkthroughs are based on marking guidance, not independently verified derivations.
1. Separate the learner's stated response from the complete task. Credit only what their response demonstrates, then identify each missing requirement; do not assume unstated working.
2. Requirement 1: Recognises credit for the stated point: States that an electrical heater is inserted into a hole in the metal block, with a thermometer used to measure the initial temperature. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
3. Requirement 2: Identifies the missing requirement: States that the heater is switched on for a measured time, with the current and potential difference recorded to calculate the electrical energy supplied, E = IVt. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
4. Requirement 3: Identifies the missing requirement: States that the final temperature of the block is recorded, so the temperature rise can be found. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
5. Requirement 4: Identifies the missing requirement: States that specific heat capacity is calculated using c = E/(mΔT), where m is the mass of the block. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
6. Requirement 5: Identifies the missing requirement: States that insulating the block reduces heat loss to the surroundings during the experiment, improving the accuracy of the result. Compare this requirement with the supplied learner response; missing evidence cannot earn credit.
7. Check the complete task again, including restrictions, units, precision and supporting evidence when relevant. Specific caution: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.
Marking points
- Recognises credit for the stated point: States that an electrical heater is inserted into a hole in the metal block, with a thermometer used to measure the initial temperature.
- Identifies the missing requirement: States that the heater is switched on for a measured time, with the current and potential difference recorded to calculate the electrical energy supplied, E = IVt.
- Identifies the missing requirement: States that the final temperature of the block is recorded, so the temperature rise can be found.
- Identifies the missing requirement: States that specific heat capacity is calculated using c = E/(mΔT), where m is the mass of the block.
- Identifies the missing requirement: States that insulating the block reduces heat loss to the surroundings during the experiment, improving the accuracy of the result.
Examiner tip: Treat each marking point as a separate requirement. Do not award the same idea twice, and do not infer work the learner did not show.