What is the power in a circuit if the current is 5 amps and the total resistance is 125 ohms?

Ohm's Law: Voltage is current times resistance.

4 amperes times 125 ohms equals 500 volts.

Power Law: Watts is voltage times current

4 amperes times 500 volts equals 2000 watts.

WARNING: This is a lot of power. Do not attempt to duplicate this in the lab

without the proper equipment as there is great risk of fire.

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Power dissipated by a resistance = (current)2 x (resistance) = (4)2 x (125) = 2000 W.

As the first contributor noted, this is a healthy amount of power dissipation. It's not

necessarily dangerous if you're prepared for it . . . hair dryers, toasters, baseboard

heaters, electric stoves and furnaces do it every day. But if you're in the engineering

lab playing with a power supply and a bagful of 1/2-watt resistors, then things will not

work out as the math predicts, since the resistors are likely to explode catastrophically

before you have a chance to read the ammeter.