Question

Two coherent sources separated by distance d are radiating in phase having wavelength l. A detector moves in a big circle around the two sources in the plane of the two sources. The angular position of n = 4 interference maxima is given as –

• A. sin^–1$\frac{n\lambda}{d}$
• B. cos^–1$\frac{4\lambda}{d}$
• C. tan^–1$\frac{d}{4\lambda}$
• D. cos^–1$\frac{\lambda}{4d}$

Answer 1

Answer: (B)

cos^–1$\frac{4\lambda}{d}$

Answer 2

d cos q = 4l

cos q = $\frac{4\lambda}{d}$ ̃ q = cos^–1$\left( \frac{4\lambda}{d} \right)$