In Young's double-slit experiment, the two slits which are separated by 1.2 mm are illuminated with a monochromatic light of wavelength 6000 overset° A . The interference pattern is observed on a screen placed at a distance of 1 m from the slits. Find the number of bright fringes formed over 1 cm width on the screen.

Question

In Young's double-slit experiment, the two slits which are separated by 1.2 mm are illuminated with a monochromatic light of wavelength 6000 overset° A . The interference pattern is observed on a screen placed at a distance of 1 m from the slits. Find the number of bright fringes formed over 1 cm width on the screen. (A) 25 (B) 12 (C) 15 (D) 20

Tardigrade Admin · Accepted Answer

Given: d=1.2 mm, λ =6000 â«=6× 10- 7 m, D=1 m, x=1 cm=1× 10- 2 m For nt h bright fringe, x=n(λ D/d) ∴ 1× 10- 2=(n × 6 × 10- 7 × 1/1.2 × 10- 3) ∴ n=(1.2 × 10- 5/6 × 10- 7)=0.2× 102=20 There are 20 bright fringes formed over 1 cm width on the screen.

$25$

$12$

$15$

$20$

25

12

15

20

Given: d=1.2mm,λ=6000Å=6×10−7m,D=1m,x=1cm=1×10−2m For nth bright fringe, x=ndλD​ ∴1×10−2=1.2×10−3n×6×10−7×1​ ∴n=6×10−71.2×10−5​=0.2×102=20 There are 20 bright fringes formed over 1cm width on the screen.

$25$

$12$

$15$

$20$