Question

The peak value of an AC passing through a 13.0 W device is 3.9 A. What is the rms voltage across it?

Answer 1

Answer: rms voltage is
`T_(rms)=2,33 V`

P = power

T = voltage

I = current

In a circuit you have that:

`P_(peak) = T_(peak) * I_(peak)` (eq 1)

The rms value of a signal X is:

`X_(rms)=X_(peak)/\sqrt(2)` (eq 2)

From eq 1,
`T_(peak) = 13 W / 3.9 A = 3,33 V`

Then, from eq 2,
`T_(rms) = 3,33 V / \sqrt(2) = 2,33 V`