A parallel beam of 500 keV photons normally incident on a sheet of lead 8 mm thick. The rate of energy transmission is 4 ^ 10^4 MeV/s. (a) What fraction of the incident photon energy absorbed in the

A parallel beam of 500 keV photons normally incident on a sheet of lead 8 mm thick. The rate of energy transmission is 4 ^ 10^4 MeV/s.

(a) What fraction of the incident photon energy absorbed in the sheet

(b) How many photons per second are incident on the sheet?

(c) What fraction of the transmitted energy due to uncollide photons?