Question

In a Young’s double slit experiment, the slits are placed 0.320 mm apart. Light of wavelength λ = 500 nm is incident on the slits. The total number of bright fringes that are observed in the angular range –30° ≤ θ ≤ 30° is:
(A) 640 (B) 320
(C) 321 (D) 641

Answer 1

Question :

In a Young’s double slit experiment, the slits are placed 0.320 mm apart. Light of wavelength λ = 500 nm is incident on the slits. The total number of bright fringes that are observed in the angular range –30° ≤ θ ≤ 30° is:

Given :

λ = 500 nm

d = 0.320 mm

θ = 30°

solution ;

we know that in YDSE.

path difference ;

dsinθ= nλ

put the given values after that ;

$0.32 \times 10 {}^{ - 3} \times \sin(30) = n \times 500 \times 10 {}^{ - 9}$

$n = \frac{0.32 \times 10 {}^{ - 3} \times 1}{500 \times 10 {}^{ - 9} \times 2}$

$n = 320$

no of maxima from -30° to 30° is

= 2n+1

= 2× 320+1

= 641

Answer 2

$\huge\underline\mathfrak\red{Answer}$

Given :

λ = 500 nm

d = 0.320 mm

θ = 30

path difference

d sinθ = nλ

n =d sinθ/λ

after putting the values you get

n = 320

maximum no bright fringes

= 2n+1

= 2× 320+1

= 641