When I was a kid listening to a transistor radio under my pillow late at night I used to wonder whether turning the volume down low would delay the gradual loss of battery voltage. My doubts centered in the fact that the volume control was (at least in those days) a variable resistor. I reasoned that turning down the volume (increasing the resistance) would merely dissipate more EMF in the form of heat, so that the actual work done by the DC cell would be insensitive to changes in the volume setting. What's the truth of the matter: would listening at low levels prolong useful battery life? If so- where was my childish reasoning faulty?