Edexcel A-Level Physics Wavefronts, Coherence and Interference

Practise Edexcel A-Level Physics wavefronts, coherence and interference through superposition, phase relationship, path difference, maxima and minima patterns.

Exam points

define coherence as a constant phase relationship, usually with the same frequency
explain constructive or destructive interference using phase and path difference
calculate maxima spacing or wavelength from interference geometry and wavefront data

[Maximum number: 3]

A student investigated the reflection of microwaves from a metal plate and a glass plate. The metal plate reflects microwaves and the glass plate partially reflects microwaves.

A plan view of the apparatus is shown.

The metal plate, the transmitter and the receiver were kept in fixed positions. The value of d was varied by moving the glass plate.

Figure for Question 2.3.39 - Wavefronts, coherence and interference question 1 — Edexcel A-Level Physics AS

As d varied, the intensity of the microwaves detected by the receiver varied.

Explain why.

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2.3.39 - Wavefronts, coherence and interference question 1