Electrical Power and Energy
Physics ⇒ Electricity and Magnetism
Electrical Power and Energy starts at 8 and continues till grade 12.
QuestionsToday has an evolving set of questions to continuously challenge students so that their knowledge grows in Electrical Power and Energy.
How you perform is determined by your score and the time you take.
When you play a quiz, your answers are evaluated in concept instead of actual words and definitions used.
See sample questions for grade 11
A 100 W lamp is switched on for 10 hours. How much energy does it use in joules?
A 1200 W microwave oven is used for 30 minutes each day for 10 days. How much energy does it consume in kWh?
A 2000 W electric kettle is used for 15 minutes. Calculate the energy consumed in kilowatt-hours.
A 240 V electric iron draws a current of 5 A. Calculate its power rating.
A 60 W light bulb is used for 5 hours. How much electrical energy does it consume in kilowatt-hours?
A device uses 500 J of energy in 10 seconds. What is its power output?
A heater is rated at 2 kW and is used for 3 hours. Calculate the total energy consumed in joules.
A toaster has a resistance of 24 Ω and is connected to a 120 V supply. Calculate the power consumed by the toaster.
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 electrical energy is often measured in kilowatt-hours rather than joules for household consumption.
Explain why high-voltage transmission lines are used to reduce energy loss during electricity transmission.
If a device operates at 230 V and draws a current of 2 A, what is its power consumption?
If the voltage across a resistor is doubled, what happens to the power dissipated by the resistor?
State the relationship between power, voltage, and resistance in an electrical circuit.
A 1500 W water heater is used to heat 10 kg of water from 20 °C to 60 °C. If the specific heat capacity of water is 4200 J/kg·°C, calculate the minimum time required (in seconds) to heat the water, assuming no heat loss.
A 250 W computer is used for 5 hours each day. If the cost of electricity is $0.12 per kWh, calculate the total cost to run the computer for 30 days.
A device is rated at 120 V, 600 W. What is the current drawn by the device when operating at its rated voltage?
A factory uses a machine that operates at 400 V and draws a current of 12 A. If the machine runs for 8 hours per day, calculate the total electrical energy consumed by the machine in one week (in kWh).
An electric motor has an efficiency of 80%. If it draws 2.5 kW of electrical power, how much useful mechanical power does it deliver?
