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 0.350 , the other an internal resistance of 0.170 . 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?