Question

Saurabh reads in his textbook that if the distance from the bulb is doubled then intensity is reduced to one-fourth. But then he notices that as a laser beam travel across the length of a room, its intensity is essentially constant. So he wants to know what geometrical characteristic of laser beam is responsible for the constant intensity, which is missing in the case of light from the bulb. His friend Samir explained him such things properly. 

(a) What values are displayed by Samir ?

(b) How does Samir explain such things properly ?

Answer 1

(a) The values displayed by Samir are : 

(i) presence of mind, 

(ii) high order of general awareness, and 

(iii) helping and caring nature. 

(b) The light beam spreads, and it propagates into spherical region. So its intensity is reduced to one -fourth in such given case. But laser beam does not spread so its intensity remains constant.