Question

In a Young's double slit experiment, the slits are separated by 0.3 mm and the screen is 1.5 m away from the plane of slits. Distance between fourth bright fringes on both sides of central bright is 2.4 cm. The frequency of light used is ______ × 10¹⁴ Hz.

विकल्प

• 5

• 7

• 9

• 11

Answer 1

In a Young's double slit experiment, the slits are separated by 0.3 mm and the screen is 1.5 m away from the plane of slits. Distance between fourth bright fringes on both sides of central bright is 2.4 cm. The frequency of light used is 5 × 10¹⁴ Hz.

Explanation:

y₄ = `(2.4"cm")/2` = 1.2cm

Position of 4^th bright fringe = `(4lambda"D")/"d"`

`(4lambda"D")/"d"` = 1.2cm      ...(i)

Putting D = 1.5, d = 3 × 10^-3 m in equation (i)

⇒ λ = `(1.2xx10^-2xx3xx10^-3)/(1.5xx4)`,  Putting λ in v = `"c"/lambda` we get

v = `"c"/lambda= (3xx10^8xx1.5xx4)/(1.2xx10^-2xx3xx10^-3)`

⇒ v = 5 × 10¹⁴ Hz