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

Question

In a Young’s double slit experiment, the two slits which are separated by 1.2 mm are illuminated with a monochromatic light of wavelength 6000 angstorm. The interference pattern is observed on a screen placed at a distance of 1m 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 mathringA =6× 10-7 m, D=1 m, x=1 cm =1× 10-2 m For nth 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=6000A˚ =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

$25$

$12$

$15$

$20$