A-LevelPhysicsWavesFeb/Mar 2017Paper 1 Q281 Mark
A monochromatic plane wave of speed c and wavelength λ is diffracted at a small aperture. The diagram illustrates successive wavefronts. [Figure showing successive wavefronts G, H and point P related to diffraction through an aperture] After what time will some portion of the wavefront GH reach point P?
A3λ
2c
B2λ
c
C3λ
c
D4λ
c
✓ Correct Answer
The correct answer is C: 3λ c
📋 Examiner Report & Trap Analysis
Common mistake: 62% of candidates selected the distractor because they confused... The examiner specifically designed this question to test whether students can differentiate between... To secure full marks, candidates must demonstrate...
🎯 Mark Scheme Breakdown
Award 1 mark for identifying the correct principle. Award 1 mark for showing clear working. Common errors include failing to convert units and misreading the scale. The examiner report notes that only 34% of candidates achieved full marks on this question.
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