Two 1.50-V batteries—with their positive terminals in the same direction—are inserted in series into the barrel of a flashlight. One battery has an internal resistance of 0.255 Ω, the other an internal resistance of 0.153 Ω. When the switch is closed, a current of 600 mA occurs in the lamp.
(a) What is the lamp’s resistance?
(b) What fraction of the chemical energy transformed appears as internal energy in the batteries?