Question

The apparent flattening of the sun at sunset and sunrise is due to
A. refraction
B. diffraction
C. total internal reflection
D. interference
E. polarization

Answer 1

Hint: Consider the effect of late sunset and early sunrise. This happens due to the phenomenon of refraction of light through the atmosphere of light. The phenomenon of apparent flattening of sun at sunset and sunrise can also be described using the same concept.

Complete step by step solution:
When light rays travel from one medium to another, the direction of light ray changes. This is called the refraction.
The density of the atmosphere is different in different layers. Due to the difference in density of the layers. The refractive index of all the layers are different. When light rays travel through the layers, the direction of the light rays slightly changes.
Light rays closer to the horizon are refracted slightly more and are raised upward most. When the light ray is far from horizon, the refraction is little less and the raising is low.
When the sun sets or rises, the lower limb is closer to the horizon and the upper limb is far from the horizon. Due to this the lower limb of the sun is raised more than the upper limb and we can see the oval sun. This is called the apparent flattening of the sun.
So, we can say that the apparent fattening of the sun is due to refraction.
The correct option is (A).

Note: When the sun is set or rises near the horizon, the light rays from the sun bends around the curve of the earth. At the time of the sunset, when we see the lower limb of the sun touching the horizon, the sun is actually set. Also, at the time of the sunrise, when the lower limb of the sun is touching the horizon, the sun is actually below the horizon about to rise. This is due to the atmospheric refraction. This effect is very small. Only near the horizon the light rays bend slightly more and we can see this effect.