Question

Calculate the speed and wavelength of light
(i) in glass
(ii) in air, when light waves of frequency `6 xx 10^14 Hz`. Travel from air to glass of `mu = 1.5`.

Answer 1

Correct Answer - (i) `2 xx 10^8 m//s ; 3.3 xx 1^-7 m`
(ii) `3 xx 10^8 m/s ; 5 xx 10^-7 m`.
Here, `v = 6 xx 10^14 Hz. Mu = 1.5`
(i) In glass,
speed of light, `v_g = (v_a)/(mu)=(3 xx 10^8)/(1.5) = 2 xx 10^8 m//s`
wavelength of light, `lamda_g = (v_g)/(v) = (2 xx 10^8)/(6 xx 10^14)`
=`3.3 xx 10^-7 m`
In air
speed of light, `v_a = c = 3 xx 10^8 m//s`
Wavelength of light, `lamda_a = (v_a)/(v)=(3 xx 10^8)/(6 xx 10^14)`
=`5 xx 10^-7 m`.