That moment when you think you've outsmarted thermodynamics with your "gotcha" question! The teacher's explaining how no electrical device can be 100% efficient because some energy always converts to heat. Then comes the student with what they think is a brilliant loophole: "What about a heater?" The teacher's face says it all. Yes, technically a heater's purpose IS to produce heat, but that doesn't make it 100% efficient - there's still energy lost through light, sound, and heat that escapes where it's not intended. The second law of thermodynamics remains undefeated, and so does the teacher's patience.