Question

A double-slit is illuminated by sodium light ( = 5893 Å). In the double-slit, the distance between
the two slits is 0.050 cm. The interference pattern is obtained on a screen placed at a distance of
1.00 metre. Calculate the distance between the fifth bright fringe on one side of the central fringe
and the fifth bright fringe on the other side.

answer- (1.18cm)​

Answer 1

Given info : A double-slit is illuminated by sodium light ( = 5893 Å). In the double-slit, the distance between

the two slits is 0.050 cm. The interference pattern is obtained on a screen placed at a distance of

1.00 metre.

To find : the distance between fifth bright fringe on one side of central Maxima to fifth fringe of the other side.

Solution : using formula, y = nλD/d

Here we have to find distance fifth bright fringe of one side of central Maxima and fifth bright side of the other one.

so, n = 5 + 5 = 10

λ = 5893 A° = 5893 × 10¯¹⁰m

D = 1 m

d = 0.05 cm = 5 × 10¯⁴ m

Now y = (10 × 5893 × 10¯¹⁰ × 1)/(5 × 10¯⁴)

= (5893/5) × 10¯⁵ m

= 1178.6 × 10¯⁵ m

≈ 1.18 cm

Therefore the required answer is 1.18 cm