Answer to Question #45941 in Molecular Physics | Thermodynamics for Azmiah

Question

Julia and Wayne heat their house during the winter with an electric heater. The thermostat
on the heater is set to 20°C and the thermostat is cycling on and off as it keeps the room
temperature stable. Julia walks out of the room leaving the lights on. Wayne tells Julia that
she is wasting electricity. Julia says that she’s not. Who is right? Discuss.

Answer 1

Looks like Julia is right. Lights in room spend energy from electric network in two ways: they give visible light (which is dissipated until an eye absorbs it) and they heat the room, because current flows through them. Hence, there is no difference - heater or lights will heat the room, as they use the same energy source.