Electrical Power and Energy
Physics ⇒ Electricity and Magnetism
Electrical Power and Energy starts at 8 and continues till grade 12.
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See sample questions for grade 12
A 100 W light bulb is used for 5 hours. How much electrical energy does it consume in kilowatt-hours (kWh)?
A 1500 W electric kettle is used to boil water for 4 minutes. Calculate the total energy used in joules.
A 200 Ω resistor is connected across a 100 V supply. Calculate the power dissipated in the resistor.
A 60 W lamp is connected to a 120 V supply. What is the current through the lamp?
A device uses 3600 J of energy in 2 minutes. What is its average power?
A heater is rated at 2 kW. If it is used for 3 hours, how much energy does it consume in kWh?
A household uses 500 kWh of energy in a month. If the cost per kWh is $0.20, what is the total cost for the month?
A refrigerator operates at 300 W and runs for 8 hours a day. How much energy does it consume in one day in kWh?
A toaster rated at 1200 W is used for 10 minutes. How much energy does it use in joules?
Describe how the efficiency of an electrical device can be calculated using power input and power output.
Describe the difference between electrical power and electrical energy.
Explain why a fuse is rated in amperes and not in watts.
Explain why electrical transmission lines are operated at high voltages to reduce energy loss.
If a device operates at 230 V and draws a current of 2 A, what is its power consumption?
State the relationship between power, energy, and time.
