Question

A charge of `6` `C` passes through a circuit every `3` `s`. If the circuit can generate `24` `W` of power, what is the circuit's resistance?

Answer 1

Current is given by `I=Q/t`, so in this case is `I=6/3=2` `A`.

Power in an electric circuit is given by `P=I^2R`, which we can rearranged to make `R` the subject: `R=P/I^2=24/2^2=6` `Omega`.

Explanation:

Very briefly as an additional explanation, we often just remember Ohm's Law, `V=IR`, and `P=VI` for power, and substitute to find the expression we need. In this case, substituting in `IR` for `V` in the law for power gives us `P=IRxxI=I^2R`.