Questions

Indus Valley Civilization flourished during 2500-1750 B.C. Indus Valley Civilization is also called as Bronze age civilization.

Physical signs of stress include Frequent colds and infections, aches, pains and tense muscles, stomach upset, loss of sexual desire, etc...

According to wave theories, for Total internal reflection tohappen: Light must travel from denser medium to rarer medium. Angle of incidence should be greater than critical angle. As in case of TIR, the image is perfectly clear, it implies that there has been no loss of intensity.

On December 21, the earth is in an equivalent position on the opposite points in its orbit, So the South pole is tipped towards the sun and North pole away from it resulting in 24 hours of darkness at the North pole, as the sun is overhead on the Tropic of Capricorn. This phenomenon is winter solstice; while on June 21, North pole is tipped towards the Sun but the South pole is tipped away from the sun resulting in 24 hours of darkness on the South Pole, as the sun is overhead on the Tropic of Cancer.This phenomenon is summer solstice; while Aphelion is the position of the earth in its orbit when it is at its distant point from the sun.