Thread: Useful energy / wasted energy HELP

please tell me about Useful energy / wasted energy of...
1. electric kettle
2. headphones

PLEASE HELP ~~

Is this homework?

1) - An electric kettle wastes energy by way of sending some of the heat into the surrounding environment (instead of all of it reaching your food)

2) - Headphones .... don't waste a lot of energy, but I guess some of the sound doesn't always reach your ears.

If you're looking for losses because of transducing one energy type to another, the conversion of electricity to sonic/kinetic energy in your headphones is probably not perfectly efficient. The conversion of electricity to heat is usually pretty efficient, however, because the conversion of anything into heat is an efficient conversion. (Most losses in any conversion are in the form of some of your energy becoming heat)