Question:
What happens to the intensity of light from a bulb if the distance from the bulb is doubled? As a laser beam travels across the length of a room, its intensity essentially remains constant. What geometrical characteristics of the LASER beam is responsible for the constant intensity which is missing in the case of light from the bulb?
Solution:
When the distance is doubled, the intensity of light becomes one-fourth.
Following are the geometrical characteristics of the LASER:
(a) unidirectional
(b) monochromatic
(c) coherent light