A compact bicycle headlight is powered by two identical alkaline cells connected in series. When the cells are fresh, the lamp draws a steady current of 210mA from the 3.0 V source.
(a) Calculate the electrical resistance of the lamp’s filament under these operating conditions. Express your answer to an appropriate number of significant figures and include units.
(b) After prolonged use, the voltage supplied by the same pair of cells drops to 2.4 V. Assuming the filament resistance remains unchanged, determine the new current through the lamp.
(c) Briefly discuss one practical consequence for the rider that follows from the change in current calculated in part (b).