Question

A plane monochromatic light falls on a diaphragm normally on two slits separated by a distance of 2.5 mm. The fringe pattern formed on a screen at 1 m distance displaces due to glass plate (m = 3/2) of thickness 10 mm placed in front of one slit. Then value of displacement is –

• A. 1 mm
• B. 2 mm
• C. 3 mm
• D. 4 mm

Answer 1

Answer: (B)

2 mm

Answer 2

Shift = (m _ 1) t . $\frac{D}{d}$

= $\left( \frac{3}{2} - 1 \right)$× $\frac{10 \times 10^{–6} \times 1}{2.5 \times 10^{–3}}$

= 2 mm