Understanding the Inverse Square Law

The inverse square law states that the intensity of radiation from a point source is inversely proportional to the square of the distance from the source.

Calculations

1. Initial Distance: The Geiger counter is initially 1 meter away from the source.

2. Final Distance: The Geiger counter is moved to 2 meters away from the source.

3. Distance Ratio: The distance has doubled (2 meters / 1 meter = 2).

4. Intensity Ratio: Since the intensity is inversely proportional to the square of the distance, the intensity will be reduced by a factor of 2² = 4.

5. New Counting Rate: Divide the initial counting rate by the intensity ratio: 396 counts/minute / 4 = 99 counts/minute.

Answer

The Geiger counter will read 99 counts per minute when it is 2 meters away from the source.