Power in Circuits Practice Problems

Batteries store energy that is used in diverse ways. The starter motor in a four-cylinder engine draws 130 A at 12 V. If the starting process lasts 2.5 s, determine the energy supplied. 

A device for administering electric shock operates at 1280V and delivers a current of 18.8 mA creating a painful shock on the target. A pulse lasts 50.0 milliseconds. Determine the power and energy delivered to the target per pulse if the current is constant.

Your household is connected to a 240 V power line. Your 13A plug fuse blows, and you replace it with the readily available 5A fuse. You connect your 75W TV and 500 W fridge through the fuse. Determine the rating of a washing machine that will blow the fuse when added to the circuit.

An electric kettle is rated at 1200 W when operating at 220 V.  Determine the resistance of the electric kettle at these operating conditions.

An electrical device runs using power supplied by two 12.0 V batteries connected in series. The resistance of the device is measured to be 5.40 Ω. If the device is used for 1 day, determine the total energy it takes from the batteries.  

A vehicle has two 12.0 V batteries connected in series. The combined batteries drive a starter motor of resistance 5.40 Ω. If the batteries are ideal, determine the power supplied to the motor.

A portable electric drill uses an 18.0 V battery. The battery stores 3.24 × 10⁵ J of electrical energy and can sustain the drill for 15 minutes for each full charge. Determine the average current supplied to the drill during operation.

An electrical circuit with two power sources is connected as shown. Determine the power at which electrical energy is converted to other energy forms in the 6.0 V power supply.

A group of students make the circuit shown below. Determine the combined rate at which the 4.0-Ω and 7.0-Ω resistors convert electrical energy into heat. 

A section of the circuit of an electrical appliance is shown below. Determine the power supplied by the 13.5 V power supply.

An electric device of "R" resistance is connected to an ideal battery with a potential difference of 1.2 V and consumes an electric power current of 0.0835 W. Determine the power current consumed by the device when it is connected to a different ideal battery with a charge of 12.0 V, assuming that "R" remains constant throughout the changes in the power current consumption.