what voltage will produce 3 A through a circuit that has 15 ohms of resistance?

The voltage required to produce 3 A through a circuit with 15 ohms of resistance is:

V = I x R
V = 3 A x 15 ohms
V = 45 volts

Therefore, a voltage of 45 volts will produce 3 A through a circuit with 15 ohms of resistance.