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 × $10^8 \,\mathrm{m}\,\mathrm{s}^{-1}$ Wavelength of reflected light = wavelength of incident light λ = 589 × $10^{-9}$ m frequency of reflected light = frequency of incident light f = $\frac{c}{\lambda}$ = $\frac{3\times10^8}{359\times10^{-9}}$ = 5.09 × $10^{14}$ Hz (b) In the process of refraction wavelength and speed changes but the frequency remain the same. Speed of light in water, v = $\frac{c}{\,\mu_w^{a}}$ = $\frac{3\times10^8}{1.33}$ = 2.26 × $10^8 \,\mathrm{m}\,\mathrm{s}^{-1}$ Wavelength of light in water λ = $\frac{v}{f}$ = $\frac{2.66\times10^8}{2.09\times10^{14}}$ = 444 × $10^{-9}$ m or λ = 444 nm