Question

Light passes through a 0.15 mm-wide slit and forms a diffraction pattern on a screen 1.25 m behind the slit. The width of the central maximum is 0.75 cm. What is the wavelength of the light?
a. 400nm
b. 450nm
c. 510nm
d. 600nm

Answer 1

Answer:

b. 450 nm

Explanation:

The wavelength of light can be calculated by using the formula derived in Young's double slit experiment. The formula is as follows:

Δx = λL/d

Δx/2 = λL/2d

where,

Δx/2 = half distance between consecutive dark fringes = width of central maximum = 0.75 cm = 0.0075 m

λ =  wavelength of light = ?

L = Distance of Screen = 1.25 m

d = width of slit = 0.15 mm = 0.00015 m

Therefore,

0.0075 m = λ(1.25 m)/(0.00015 m)

λ = (0.0075 m)(0.00015 m)/2(1.25 m)

λ = 4.5 x 10⁻⁷ m = 450 nm

Thus, the correct option is:

b. 450 nm