Question

A primary coil of a transformer is connected to a 120V/60Hz wall outlet. The secondary coil is connected to a lamp that dissipates 60 W. How do I find the rms current in the primary coil?

Answer 1

0.5Amperes

Step-by-step explanation:

Using the conservation of power formula

P = VI

The power we have in this coil is given as

P = 60 watts

Then we have V = 120 watts

Such that when we put these values into the formula above we will get:

60 = 120I

Then when we divide through by 120:

I = 60/120

I = 0.5 amperes

So 0.5 amperes is the rms in the primary coil.