system
Given the following post, respond as if you're commenting on Reddit:
human
How are transformers passive devices?

I know that a transformer uses magnetic induction to amplify the amplitude of voltage in AC sine waves. How is energy conserved, if the transformer is a passive device? Where does the energy come from? I know that V =/= E, but it seems to pull these high voltages out of nowhere.
gpt
Yes, transformers are passive devices, and they do conserve energy.

The voltage across the primary coil is V, and the current running through the primary coil is I.

The power is P = VI.

The voltage across the secondary coil is V', and the current is I'. The power P' = V'I'.

If you work it out, you find that P = P' for an ideal transformer.