3.4 Electric Power

Which one of the following quantities is equivalent to 1 W?

• 1 V/A

• 1 Ω • m

• 1 V • A

• 1 V/Ω

A kilowatt-hour is equivalent to

• 1000 W.

• 3600 J.

• 3,600,000 J/s.

• 3,600,000 J.

When 5.00 A is flowing through an 10.0-Ω device, how much power is being dissipated in the device?

• 50.0 W

• 250 W

• 500 W

• 2.50 kW

A light bulb operating at a dc voltage of 100 V has a resistance of 200 Ω. How much power is dissipated in this bulb?

• 100 W

• 60 W

• 50 W

• 200 W

A 200-W light bulb is connected across a 100-V dc power supply. What current will flow through this bulb?

• 0.90 A

• 0.36 A

• 0.60 A

• 2.0 A

If electricity costs $0.15 per kWh, how much does it cost to operate the heater from before (P = 10.1 W) for 30 days?

• $0.19

• $0.001

• $1090.80

• $1.09

How is electrical energy usually produced?

• Fuel is burned to produce smoke, which turns a turbine.
• Fuel is burned to heat water and produce steam, which turns a turbine.
• Hot fuel is placed in water to produce steam, which then turns a turbine.
• A turbine blows hot steam onto fuel, which heats it up and produces electricity.

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Why do many traditional methods of electrical energy production lead to global warming?

• After the fuel is burned it leaks dangerous chemicals.
• The heat that burning fuel produces directly leads to global warming.
• Burning traditional fuel produces nitrogen gas.
• Burning traditional fuel produces carbon dioxide.

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The power of an appliance is...

• the amount of voltage going through it

• the amount of energy it consumes per second

• the number of resistors it contains

A 3000 watt electric dryer is on for one hour. How long would a 1000 watt microwave have to be cooking in order to use the same amount of electricity as the dryer.

• 10 minutes

• 24 hours

• 3 hours

• 30 minutes

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