Complete module assessment with 15 multiple choice questions and 5 written-response questions grounded in this module's lesson content.
Q1. All electromagnetic waves in a vacuum have the same:
Q2. The speed of light relation is:
Q3. Young's double slit experiment provides evidence for light's:
Q4. A diffraction grating separates colours because different wavelengths:
Q5. Polarisation shows that light is:
Q6. Absorption lines in a stellar spectrum can identify:
Q7. The wave model of light explains interference by using:
Q8. Einstein's special relativity postulates include that the speed of light in vacuum is:
Q9. A moving clock observed from an inertial frame runs:
Q10. Length contraction occurs along:
Q11. The rest energy of a particle is:
Q12. Special relativity shows that simultaneity is:
Q13. In the photoelectric effect, increasing light intensity above threshold mainly increases:
Q14. Photon energy is given by:
Q15. Wave-particle duality means light:
Q16. Explain how interference, diffraction and polarisation support the wave model of light.
Q17. Explain how spectroscopy links wave behaviour to astronomical information.
Q18. Summarise the two postulates of special relativity and explain one consequence for time or length.
Q19. Explain why the photoelectric effect supports the photon model of light.
Q20. Compare the wave model, photon model and relativistic model of light.
Q1: B
Q2: C
Q3: D
Q4: A
Q5: B
Q6: D
Q7: C
Q8: A
Q9: B
Q10: D
Q11: C
Q12: A
Q13: D
Q14: B
Q15: C
Interference shows that light waves superpose to produce bright and dark regions. Diffraction shows light spreading around apertures or gratings, with wavelength-dependent angles. Polarisation shows that light oscillations are transverse because only transverse waves can be polarised. Together these observations support the electromagnetic transverse wave model of light.
Marks: 1, interference | 1, diffraction | 1, wavelength dependence | 1, polarisation | 1, transverse EM conclusion
Atoms absorb and emit light at specific wavelengths because electron energy levels are quantised. A star's absorption spectrum contains dark lines corresponding to elements in its outer layers. Comparing these lines with laboratory spectra identifies chemical composition. Shifts in spectral lines can show relative motion through redshift or blueshift, connecting wave properties to astronomical observations.
Marks: 1, quantised wavelengths | 1, absorption/emission lines | 1, element identification | 1, redshift/blueshift | 1, astronomy link
The first postulate is that the laws of physics are the same in all inertial frames. The second is that the speed of light in vacuum has the same value for all inertial observers, regardless of source or observer motion. A consequence is time dilation: a moving clock is observed to run slow relative to a clock at rest in the observer's frame. Another is length contraction along the direction of relative motion.
Marks: 1, laws same | 1, c constant | 1, independence from source/observer | 1, time dilation or length contraction | 1, direction/frame detail
The photoelectric effect shows that electrons are emitted only when light frequency exceeds a threshold, no matter how intense lower-frequency light is. Emission occurs without measurable delay above threshold. The maximum kinetic energy depends on frequency through Kmax = hf - phi, not on intensity. Intensity mainly changes the number of emitted electrons. These results support photons with energy E = hf.
Marks: 1, threshold frequency | 1, no delay | 1, kinetic energy-frequency relationship | 1, intensity effect | 1, photon energy
The wave model explains interference, diffraction and polarisation using transverse electromagnetic waves. The photon model explains quantised interactions such as the photoelectric effect, where light transfers energy in packets E = hf. Special relativity treats the speed of light in vacuum as invariant for all inertial observers, leading to time dilation, length contraction and relativity of simultaneity. Modern physics uses the model that fits the evidence and recognises wave-particle duality.
Marks: 1, wave model | 1, photon model | 1, relativity/invariant c | 1, consequences | 1, duality/model choice
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