Light of wavelength falls on a double-slit arrangement having separation

PHYSICS · Single correct · A Level · Physics · Waves · Waves

Problem

Light of wavelength

\lambda=5890\,\text{\AA}

falls on a double-slit arrangement having separation

d=0.2\,\text{mm}

. A thin lens of focal length

f=1\,\text{m}

is placed near the slits. The linear separation of fringes on a screen placed in the focal plane of the lens is (1)

3\,\text{mm}

(2)

4\,\text{mm}

(3)

2\,\text{mm}

(4)

1\,\text{mm}