A beam of 1-MeV gamma rays incident on a piece of 0.50-cm thick lead is reduced by 50% of its initial value. How thick must the lead be to reduce the beam to one percent of its initial value?

Question

Quizplus · Accepted Answer

The attenuation of gamma rays follows an exponential decay model. If 0.50 cm reduces the intensity by 50%, then each 0.50 cm reduces the intensity by half. To reduce the intensity to 1%, we need to solve (1/2)^(x/0.5) = 0.01, which gives x = 3.3 cm.

A Beam of 1-MeV Gamma Rays Incident on a Piece