Question

Light of wavelength 5 × 10^–7 m falls on a pair of narrow slits separated by a distance d. The interference pattern on a screen placed 2m away shows that there is darkness at the positions exactly opposite to each slit. The separation between the slits is –

• A. 0.5 mm
• B. 1 mm
• C. 2 mm
• D. 5 × 10^–7 mm

Answer 1

Answer: (B)

1 mm

Answer 2

$\frac{\mathbf{d}}{\mathbf{2}}$ = $\frac{D\lambda}{2d}$ ̃ d² = Dl

\ d = $\sqrt{D\lambda}$= 10^–3m = 1mm