Light of wavelength 5000 Å 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

Reflection does not change wavelength.
Frequency remains unchanged both in reflection and refraction.
` therefore lamda = 5000Å . " again " , v = c/lamda = (3 xx 10^8)/(5000 xx 10^(-10)) Hz`
` = 6 xx 1014 Hz`
Again i = r and i + r `= 90^@`
` therefore i = 45^@`