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Question
Monochromatic light of wavelength 600 nm is incident from the air on a water surface. The refractive index of water is 1.33. Find the
- wavelength,
- frequency and
- speed, of reflected and refracted light.
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Solution
Given: λ = 600 nm, µ = 1.33
(i) In reflection, the ray will reflect back in the same medium as that of the incident ray.
Hence, wavelength (λ) = 600 nm
(ii) Frequency = υ = `"c"/λ = (3 xx 10^8)/(600 xx 10^-9)`
= 0.5 × 1015 Hz
(iii) Speed = 3 × 108 ms−1
In refraction, the speed and wavelength change while the frequency remains the same.
Hence, speed = ν = `"c"/µ = (3 xx 10^8)/(1.33)`
= 2.26 × 108 ms−1
Wavelength = λ = `ν/υ`
= `(2.26 xx 10^8)/(0.5 xx 10^15)`
= 4.52 × 10−7 m
= 452 nm
Frequency = υ = 0.5 × 1015 Hz
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