Q17DQ - University Physics with Modern Physics

Question

 Monochromatic light is directed at normal incidence on a thin film. There is destructive interference for the reflected light, so the intensity of the reflected light is very low. What happened to the energy of the incident light?

Step-by-Step Solution

Answer

 The transmitted light carries the energy of the incident light.

Step 1: (a) Concept of interference.

The fraction of light reflected from a surface is called the reflectivity of that surface and the fraction of light transmitted through the surface is called Transmittivity.

Step 2: (b) Explanation of the argument.

The reflected beams from the upper and bottom surface of the film undergo destructive interference which causes the intensity of the light to be low. The transmitted beam undergoes constructive interference and carries the energy of the incident wave which makes the light beam appear brighter as compared to the reflected beam.