Energy Calculations (J & kWh)

What is the formula to calculate electrical energy (E) if you know the power (P) in watts and the time (t) in seconds?

If a device uses 100 watts of power for 3 hours, how much energy in joules has it consumed?

• 300 J

• 1080 J

• 1080000 J

• 360000 J

A heater runs for 4 hours using 1500 watts of power. How many kilowatt-hours of energy does it use?

• 1.5 kWh

• 6 kWh

• 6000 kWh

• 0.6 kWh

Calculate the energy in joules used by a 40-watt bulb that is on for 25 seconds.

• 1000 J

• 100 joules

• 10000 joules

• 250 joules

If an appliance consumes 0.5 kilowatts of power and operates for 10 hours, how many kilowatt-hours of energy does it use?

• 0.05 kWh

• 5 kWh

• 50 kWh

• 500 kWh

What is the energy consumption in J of a 200-watt device running for 2 minutes?

• 24000 J

• 1200 J

• 400 J

• 2400 J

A factory operates a machine that uses 15 kilowatts of power for 3 hours daily. How much energy, in kilowatt-hours, does the machine consume each day?

• 45 kWh

• 450 kWh

• 4.5 kWh

• 0.45 kWh

How many joules of energy are used by a 75-watt light bulb that runs for 10 minutes?

• 45000 J

• 7500 J

• 4500 J

• 750 J

A microwave uses 1200 watts of power and is used for 90 seconds. How much energy in joules does it consume?

• 108000 J

• 1800 J

• 10800 J

• 18000 J

If a television uses 0.1 kilowatts of power and runs for 10 hours, how many kilowatt-hours of energy does it consume?

• 1 kWh

• 10 kWh

• 0.01 kWh

• 0.1 kWh