Question

A charge of `25 C` passes through a circuit every `4 s`. If the circuit can generate `1 W` of power, what is the circuit's resistance?

Answer 1

The circuit resistance is `=25.6mOmega`

Explanation:

We apply the equation

`Q=It`

The charge is `Q=25C`

The time is `t=4s`

The current is `I=Q/t=25/4A`

The power

`P=UI`

But according to Ohm's Law

`U=RI`

So,

`P=RI*I=RI^2`

So,

the resistance is `R=P/I^2`

`=1/(25/4)^2=0.0256Omega`