Question

Q24. Light of wavelength 400 nm in air, enters a glass slab of refractive index 1.5. Find (Given 1 nm = 10-9 m)
(i) Speed
(ii) Frequency
(iii) Wavelength of light in glass​

Answer 1

Answer:

Explanation:

• Speed  = 2 x 10^8 m/s

As, η = c/v

so, v = c/η

v = (3 x 10^8 m/s) / 1.5

v = 2 x 10^8 m/s

• Frequency doesn't change from one medium to another so

Calculating frequency in air by formula

V(in air) = f x λ

so f = V / λ

f = 3 x 10^8 m/s / 400 nm

On calculating

f = 7.5 x 10^14 Hz

• Wavelength in glass:-

V(in glass) = f x λ(in glass)

So, λ(in glass) = V / f

λ = (2 x 10^8 m/s) / (7.5 x 10^14)

λ = 2.6 x 10^-7 m