Soln. (a) In the process of reflection wavelength, frequency and speed of incident light remain unchanged.
So, speed of reflected light = speed of incident light, c = 3 × 108ms–1
Wavelength of reflected light = wavelength of incident light
λ = 589 × 10–9 m
frequency of reflected light = frequency of incident light
f =

c

λ

=

3×108

359×10−9

= 5.09 × 1014 Hz
(b) In the process of refraction wavelength and speed changes but the frequency remain the same.
Speed of light in water, v =

c

a ‌ µw

=

3×108

1.33

= 2.26 × 108ms−1
Wavelength of light in water
λ =

v

f

=

2.66×108

2.09×1014

= 444 × 10−9 m or λ = 444 nm