Question

Monochromatic light with wavelength of 750 nm passes through two narrow slits. If the slits are( 25 x10-6 m) apart, at what angle will the fourth order bright fringe appear on a viewing screen?

Answer 1

The angle at which the m-th order bright fringe occurs

$$\sin\theta=\frac{m\lambda}{d}$$

$$\sin\theta=\frac{4\times 750\times 10^{-9}\:\rm m}{25\times 10^{-6}\:\rm m}=0.12$$

$$\theta=6.89^{\circ}$$