When light crosses over from one medium to another, it changes its speed but the direction remains the same

Question

TRUE

FALSE

Answer 1

Not so. Going from one medium to another will often change light's direction.

If the index of refraction of medium 1 is n1 and that of medium 2 is n2, then the angle of refraction (measured against a perpendicular to the interface) is @2 for an angle of incidence @1, according to Snell's law:(using @ for the Greek theta):

n1 sin@1 = n2 sin@2

The index of refraction is the ratio of the speed of light in a vacuum (3.0 x 10^8 m/s) to the speed of light in the medium.

Unless the light is directed perpendicularly to the medium [sin@1=0], it will be bent at the interface.

The light's frequency remains constant, but its wavelength will change, such that the speed in the medium is (f) (lambda), the product of frequency and wavelength.