A Geiger counter placed 1 meter from a point source of radiation registers 100 counts per second.If the Geiger counter is moved closer - to 0.5 meter from the source - what will the count rate be?
A)25 counts/s
B)50 counts/s
C)100 counts/s
D)200 counts/s
E)400 counts/s

Question

Quizplus · Accepted Answer

The intensity of radiation follows the inverse square law, meaning it is inversely proportional to the square of the distance from the source. If the distance is halved (from 1 meter to 0.5 meter), the intensity (and thus the count rate) will increase by a factor of 4 (since (1/0.5)^2 = 4). Therefore, the count rate will be 400 counts/s.

A Geiger Counter Placed 1 Meter from a Point Source