Chapter 23, Problem 11Q

To determine

To Explain:

A white beam of parallel light enters water at an angle, the beam broadens.

Answer to Problem 11Q

Solution:

A beam of white light, each undergoes the above explained refraction, collectively produces the broader beam of refracted rays. Hence, the resultant refracted rays are the broader beam.

Explanation of Solution

The parallel light beams tend to move towards normal as they enter water from air due to the refraction. Since light is falling on the surface at an angle, hence there are beams which fall on the surface first while there are beams which travel longer in the air. Hence different light rays refract at different times and all bend towards normal, causing a spread in the refracted beam of light.

The white light comprises of the seven rays each having different wavelength. In air, the speed is only slightly less. In other transparent materials, such asglass and water, the speed is always less than that in vacuum. The constituent colors are moving with different velocities as it enters the water. Hence, each white ray bents in the water at different angle giving cluster of rays.