IIT JEE , AIEEE Forum - Physics , Optics

vaiko

sir, it is known thatwen light changes its medium its velocity decreases, but agin wen it emerges in the same med its velocity becomes as it was... how does it happen?

him26.89

vel. of light in any med. = vel. in vacuum/refractive index of medium.

when light ray comes back then the index is same again.

caprio.nups

velocity is inversely proportional to refractive index of medium...so as the medium changes velocity changes..

when light emerges from the medium, refractive index again changes...so velocity becomes equal 2 d original velocity...

I hope this is clear nw...

bujji

The frequency remains constant. The wavelength is inversely prop to ref. index.

krishna.gopal

good answers by everyone, but i don't think that they answer the HOW part of it because refractive index itself is defined in terms of velocity so ou can't say that velocity is increasing because refractive index is decreasing. the velocity of light depends on electric and magnetic properties of matter and velocity increases because of change in these properties

elessar_iitkgp

If you want to understand HOW this occurs, Huygens construction (given in every standard textbook) will prove useful.
Light is an electromagnetic wave comprising of electric and magnetic components. We usually study light using the electric component. In higher physics, reflection & refraction can be explained in terms of this electric vector. But don't try to break ur head trying to understand this. Read up Huygen's construction. That should be fairly good explaination

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