Wave Phenomena (Reflection, Refraction, Diffraction, Interference) — A/L Physics

How do I practise Wave Phenomena (Reflection, Refraction, Diffraction, Interference)?

1 question with a worked solution

1. What fundamental condition must be satisfied by two wave sources to produce an observable, steady and sustained interference pattern?
   1. A) Sources must be mutually coherent with a constant phase difference and identical frequency
   2. B) Sources must emit random bursts of white light at unequal velocities
   3. C) Sources must have widely differing wavelengths and orthogonal polarization
   4. D) Sources must be separated by a distance much larger than 10,000 wavelengths
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   Correct answer: A) Sources must be mutually coherent with a constant phase difference and identical frequency

   Sustained interference requires coherent wave sources—meaning they emit waves of the same frequency and wavelength with a constant (time-invariant) phase difference. Without coherence, rapid random phase shifts wash out the constructive and destructive nodes into uniform illumination.

   Show worked solution

   Step 1: Review conditions for sustained interference. Step 2: Coherence is essential: same frequency and constant phase relationship. Answer: Sources must be mutually coherent with a constant phase difference and identical frequency.
   Modelled on: the A/L Physics examination pattern

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Where does Wave Phenomena (Reflection, Refraction, Diffraction, Interference) fit in the syllabus?

Unit 3.3 · Year 1 · Term 2