Question

If a current of `3 A` passing through a circuit generates `45 W` of power, what is the resistance of the circuit?

Answer 1

Resistance `= 5 Omega`

Explanation:

For electical circuits:

`"Power" = "Voltage" xx "Current"`
`color(white)("XXX")`and
`"Voltage" = "Current"xx"Resistance"`

We are told:
`color(white)("XXX")45W = "Voltage" xx 3A`

`color(white)("XXX")45W = (3Axx"Resistance")xx3A`

`color(white)("XXX")45W = 9A^2 xx "Resistance"`

`color(white)("XXX")"Resistance" = (45W)/(9A^2)=5 W/(A^2) = 5 Omega`

`color(white)("XXXXXXXXX")`since `1" ohm "(Omega) = (1 " watt" (W))/(1 " amp"^2 (A^2))`