A parallel beam of monochromatic light of wavelength 5000Å is incident normally on a single narrow slit of width 0.001 mm. The light is focused by a convex lens on a screen placed in focal plane. The first minimum will be formed for the angle of diffraction equal to

Question

A parallel beam of monochromatic light of wavelength 5000Å is incident normally on a single narrow slit of width 0.001 mm. The light is focused by a convex lens on a screen placed in focal plane. The first minimum will be formed for the angle of diffraction equal to (A) 0o (B) 15o (C) 30o (D) 50o

Tardigrade Admin · Accepted Answer

For first minimum, asin θ = n λ = 1 λ sin θ = (λ /a) = (5000 × 10- 10/0.001 × 10- 3) = 0.5 θ =30o

Q. A parallel beam of monochromatic light of wavelength $5000Å$ is incident normally on a single narrow slit of width 0.001 mm. The light is focused by a convex lens on a screen placed in focal plane. The first minimum will be formed for the angle of diffraction equal to

$0^{o}$

$1 5^{o}$

$3 0^{o}$

$5 0^{o}$

For first minimum, $a s in θ = nλ = 1 λ$
$s in θ = \frac{λ}{a} = \frac{5000 \times 1 0 ^{- 10}}{0.001 \times 1 0 ^{- 3}} = 0.5$
$θ = 3 0^{o}$

Q. A parallel beam of monochromatic light of wavelength 5000Å is incident normally on a single narrow slit of width 0.001 mm. The light is focused by a convex lens on a screen placed in focal plane. The first minimum will be formed for the angle of diffraction equal to

0o

15o

30o

50o