Physics
Quantum and nuclear processes
- 1.
Find energy in joules of a photon of frequency 5.00e14 Hz. Use h = 6.63e-34 J s. Explain why doubling beam intensity at fixed frequency does not double photon energy.
[3 marks] - 2.
A stationary uranium-238 nucleus emits an alpha particle. State the daughter's mass and proton numbers and explain why it recoils. Neglect photon emission.
[3 marks] · no calculator - 3.
An atom emits a photon when its electron moves from -1.50 eV to -3.50 eV. Find wavelength using h = 6.63e-34 J s, c = 3.00e8 m s^-1 and 1 eV = 1.60e-19 J. Explain why the atom loses energy.
[3 marks] - 4.
A sample initially contains 2.00e12 radioactive nuclei and has half-life 6.00 hours. Find decay constant in s^-1 and activity after 12.0 hours. Assume no daughter contribution. Give 3 significant figures.
[3 marks] - 5.
An electron initially at rest is accelerated through 150 V in vacuum. Find its de Broglie wavelength using e = 1.60e-19 C, m = 9.11e-31 kg, h = 6.63e-34 J s. Use non-relativistic mechanics and justify that assumption from its speed with c = 3.00e8 m s^-1.
[3 marks] - 6.
A nucleus with mass number 4 has mass defect 0.0300 u relative to separated nucleons. Use 1 u = 1.66e-27 kg, c = 3.00e8 m s^-1 and 1 MeV = 1.60e-13 J. Find total binding energy and binding energy per nucleon. Explain the sign of energy needed to separate it.
[3 marks]
Marking points are indicative, not an official mark scheme. Accept equivalent valid methods and supported interpretations that address the task; award each mark once without requiring the model wording.