Question

A charge of `8 C` passes through a circuit every `2 s`. If the circuit can generate `3 W` of power, what is the circuit's resistance?

Answer 1

I found: `0.2Omega`

Explanation:

You know that current `I` is the rate of passing of charge `Q` through a section of a conductor with time `t` or:

`I=Q/t`

in your case:
`I=8/2=4A`

Power `P` is the rate of transformation of energy with time that, in case of electrical circuits, can be written (using also Ohm's Law: `V=RI`):

`P=VI=V^2/R=I^2R`

using the last one:

`P=I^2R` and rearranging:

`R=P/I^2=3/4^2=3/16=0.1875~~0.2Omega`