Explain the following, giving reasons:
(i) When monochromatic light is incident on a surface separating two media, the reflected and refracted light both have the same frequency as the incident frequency.
(ii) When light travels from a rarer to a denser medium, the speed decreases. Does this decrease in speed imply a reduction in the energy carried by the wave?
(iii) In the wave picture of light, intensity of light is determined by the square of the amplitude of the wave. What determines the intensity in the photon picture of light?
Answers
Reasons are given below :
i) When monochromatic light is incident on a surface separating two media, the reflected and refracted light both have the same frequency as the incident frequency.
• Reason : As frequency do not depends on refractive index of media, It only depends on the source producing light.
ii) When light travels from a rarer to a denser medium, the speed decreases. No, this decrease in speed doesn't imply a reduction in the energy carried by the wave
• Reason : Energy carried by a wave depends on the amplitude of the wave, not on the speed.
iii ) In the wave picture of light, intensity of light is determined by the square of the amplitude of the wave.
• The number of photon incident normally on crossing a unit area per unit time determines the intensity in the photon picture of light