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 9
A 100 W lamp is switched on for 3 hours. How much energy does it use in Joules?
A 1200 W microwave oven is used for 10 minutes. How much energy does it use in kWh?
A 1500 W geyser is used for 20 minutes. Calculate the energy consumed in kWh.
A 200 W computer is used for 5 hours. How much energy does it consume in kWh?
A 120 V toaster draws a current of 4 A. Calculate the energy consumed in 15 minutes in joules.
A 60 W bulb and a 100 W bulb are connected in parallel to a 220 V supply. Which bulb will consume more energy in 5 hours, and by how much (in kWh)?
A 60 W lamp is left on continuously for 7 days. Calculate the total energy consumed in kilowatt-hours (kWh).
A device is rated at 500 W, 230 V. If it is operated for 2 hours, calculate the total charge (in coulombs) that flows through it during this time.
Which of the following appliances uses the most electrical energy in one hour?
(1) 100 W fan
(2) 60 W bulb
(3) 1500 W heater
(4) 200 W TV
Which of the following is a correct statement about energy and power?
(1) Power is the total energy used
(2) Energy is the rate at which power is used
(3) Power is the rate at which energy is used
(4) Energy and power are the same
Which of the following is NOT a correct formula for power?
(1) P = V × I
(2) P = I² × R
(3) P = V² / R
(4) P = R / V
Which of the following is NOT a correct unit for power?
(1) Watt
(2) Joule/second
(3) Kilowatt
(4) Joule
Fill in the blank: 1 kilowatt (kW) is equal to ________ watts.
Fill in the blank: The cost of electrical energy used in homes is usually calculated based on the number of ________ consumed.
Fill in the blank: The energy consumed by an appliance is equal to its power multiplied by the ________ it is used for.
Fill in the blank: The power consumed by a resistor can also be calculated using the formula P = ________ / R.
True or False: A 100 W bulb consumes more energy per hour than a 60 W bulb.
True or False: Increasing the resistance in a circuit while keeping the voltage constant will decrease the power consumed.
True or False: The energy consumed by an appliance depends on both its power rating and the time it is used.
True or False: The higher the power rating of an appliance, the more energy it will use in a given time.
