At a voltage of 120 V in an electric lamp for 0.5 minutes, 900 J of energy was consumed.

At a voltage of 120 V in an electric lamp for 0.5 minutes, 900 J of energy was consumed. Determine what the current in the circuit is equal to.

U = 120 V.

t = 0.5 min = 30 s.

Q = 900 J.

I -?

The amount of heat Q that is released in a conductor with a current is determined by the Joule-Lenz law: Q = I * U * t, where I is the current in the conductor, U is the voltage at the ends of the conductor, t is the time it passes through the conductor.

We express the current strength I by the formula: I = Q / U * t.

I = 900 J / 120 V * 30 s = 0.25 A.

Answer: the current in the circuit is I = 0.25 A.