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 10
Explain why electrical energy is transmitted at high voltages over long distances.
If a bulb is rated 100 W, what does this rating mean?
If the voltage across a resistor is doubled, what happens to the power dissipated by the resistor (assuming resistance is constant)?
If two bulbs of 60 W and 100 W are connected in parallel to a voltage supply, which bulb will glow brighter?
State the relationship between electrical energy, power, and time.
A 150 W television is used for 2 hours daily for 15 days. Calculate the total energy consumed in kilowatt-hours (kWh).
A 2000 W water heater is used for 45 minutes. Calculate the total energy consumed in joules.
A 60 W bulb and a 100 W bulb are connected in series to a 220 V supply. Which bulb will glow brighter?
Which formula can be used to calculate power if only current and resistance are known?
(1) P = I²R
(2) P = V/I
(3) P = V²/R
(4) P = IR
Which of the following appliances will consume more electrical energy if used for the same amount of time?
(1) 60 W fan
(2) 100 W bulb
(3) 40 W tube light
(4) 75 W heater
Which of the following is NOT a correct pair?
(1) Power – Watt
(2) Energy – Joule
(3) Power – Joule
(4) Energy – kWh
Which of the following is NOT a unit of power?
(1) Watt
(2) Joule/second
(3) Kilowatt
(4) Joule
Fill in the blank: The commercial unit of electrical energy is ________.
Fill in the blank: The rate at which work is done or energy is transferred in an electric circuit is called ________.
The energy consumed by a 200 W device in 3 hours is ________ kWh.
The power consumed by a device is 60 W and it operates for 2 hours. The total energy consumed is ________ Wh.
True or False: Power is the rate at which electrical energy is transferred by an electric circuit.
True or False: The higher the power rating of an appliance, the more energy it will consume in a given time.
True or False: The power consumed by a resistor is given by P = V²/R.
True or False: The unit of electrical energy in the International System of Units (SI) is the kilowatt-hour (kWh).
