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When light travels from a rarer to denser medium, it loses some speed. Does the reduction in speed imply a reduction in the energy carried by the light wave ? |
Answer» We know that total average energy density associated with an electromagnetic wave (i.e. light wave) is `u_(av) = (B_(0)^(2))/(2mu_(0)) = (1)/(2) in_(0)E_(0)^(2)` This shows that `u_(av)` depends upon `B_(0) and E_(0)` (i.e. the amplitude of magnetic vector and eletric vector). `u_(av)` is independent of the speed of wave propagation. Therefore, the wave may lose speed, but not the energy. |
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