Two coherent in-phase point sources are separated by 5.2λ. A circular observation path is centred at their midpoint and encloses both sources. During one complete revolution, how many positions of maximum intensity are encountered?
Physics · Wave Optics · interferece of light and huygen principle
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Question

Two coherent in-phase point sources are separated by 5.2λ. A circular observation path is centred at their midpoint and encloses both sources. During one complete revolution, how many positions of maximum intensity are encountered?

Physics · Wave Optics · interferece of light and huygen principle

G1 Physics · Accepted Answer

The signed path difference varies between −5.2λ and +5.2λ. For maxima, Δ = nλ. Allowed integers are n = −5, −4, −3, −2, −1, 0, 1, 2, 3, 4, 5. There are 11 allowed values. Each lies strictly inside the extreme range and therefore occurs at two points on the circle. Thus, number of maxima = 11×2 = 22. Hence the answer is 22.