Question

Radiation of wavelength 2 × 10^–3 m falls on a slit of width 4 × 10^–3 m. The angular spread of the central maximum will be –

• A. 30⁰
• B. 60⁰
• C. 90⁰
• D. 180⁰

Answer 1

Answer: (B)

60⁰

Answer 2

For 1^st minima on either side

sin q = $\frac{\lambda}{a} = \frac{2 \times 10^{- 3}}{4 \times 10^{- 3}}$

\ q = 30**⁰**

\ Angular width of central maxima = 2q = 60**⁰**