Electrical Power Worksheet
Name:____________________________________________________
Mod:____________________
Date:____________________
Directions: Answer the following problems below. Make sure to list the equation(s) that were
used, show all work and write all units.
1. Derive how power is equal to voltage multiplied by current based off the idea that
power is equal to work per time.
P = W/t → P = V I
2. A 60 watt light bulb is turned on once the switch is lifted. If the voltage is 120 volts, how
much current is flowing through the light bulb?
3. Inside a television a 34 ohm resistor is placed in a circuit that has 7.9 amperes flowing
through it. What is power usage of the television?
4. A homeowner is trying to decide whether to leave a light bulb on all night. The light
bulb is a 60W bulb and would be left on for approximately 7.5 hours per night. His
electric company charges $0.1099 per kWh for electrical energy. Over the course of a
month (30 days) how much would it of cost the person to leave the light on?
Electrical Power Worksheet
Methacton High School Physics Department
1
5. A person replaces a 100W bulb with a 75W bulb. The light is used about 3.0 hours per
day. Approximately how much money can the person expect to save on the next
electric bill (30 day period) if the cost of electrical energy is $0.10 per kWh?
6. A 6,000 BTU Air Conditioner uses about 750 watts of electrical power to cool a room
while it is turned on. If the air conditioner is used for 8 hours a day over the course of 1
month (30 days), how much would it cost a person to cool their room at a cost of
$0.1099 per kWh?
Electrical Power Worksheet
Methacton High School Physics Department
2