Light of wavelength `5000Å` falls on a plane reflecting surface. What are the wavelength and frequency of reflected light ? For what angle of incidence is the reflected ray normal to the incident ray ?

Explanation

wavelength of incident `Å = 5000 xx10^(-10)` m
Speed of light `C=3xx10^(8)` m
Freuency of incident light is given by the relation ,
`V=( C)/(lamda)`
`=(3xx10^(8))/(5000xx10^(-10))=6xx10^(14)` Hz
the wavelength and frequency of indent light is the same as that of refected ray.
Hence the wavelrngth of reflected light is 5000 `Å` and its frequancy is `6xx10^(14)` Hz . When reflected , angle r is `90^(@)`
Accoding to the law of reflection , the angle of incidence is alwayes equal to the angle of reflection , Hence we can write the sum as :
angle i+ angle r =90
angle i + angle i =90
angle `=(90)/(2) = 45^(@)`
therefore , the angle of incldence for the given consition is `45^(@)`