Electric Current & Power

If an electric water heater uses 40 kW of power and runs for 8 hours, what is the total amount of energy used?

• 5 kilowatt-hours

• 48 kilowatt-hours

• 32 kilowatt-hours

• 320 kilowatt-hours

According to Ohm’s law, resistance is equal to voltage divided by

• time.

• current.

• conduction.

• potential.

According to Ohm’s law, what is the resistance of a light if the voltage is 9.0 volts and the current is 0.30 amps?

• 0.033 ohms

• 30 ohms

• 2.7 ohms

• 8.7 ohms

In a series circuit with three bulbs,

• there are many paths for the current to take.

• all of the bulbs become dimmer as more bulbs are added.

• the remaining two bulbs are not affected if one bulb burns out.

• a switch is never used.

In a series circuit with three bulbs, adding another bulb will

• make the nearest bulb brighter.

• make all the bulbs brighter.

• make some of the bulbs dimmer.

• make all the bulbs dimmer.

In a parallel circuit with three bulbs,

• the bulbs must all be located on the same branch.

• current from each bulb has its own path.

• there is only one path for the current to take.

• the overall resistance increases if a new branch is added.

A device to measure electrical potential energy difference, or voltage, is called a(n)

• ammeter.

• series meter.

• voltmeter.

• Ohm meter.

A connection that allows current to take the path of least resistance is called a

• short circuit.

• parallel circuit.

• series circuit.

• grounded circuit.

What is a disadvantage of using fuses?

• When a fuse burns out, it cannot be used again.

• A fuse contains a thin strip of metal that can melt.

• A fuse shuts off when the current gets too high.

• A fuse prevents circuits from overheating.

What effect would a current of greater than 0.2 amp have on your body?

• It would be almost unnoticeable.

• It could cause burns and stop your heart.

• It might cause an irregular heartbeat and disrupt the flow of blood.

• It would feel like a shock you get from touching a doorknob.