Advertisements
Advertisements
Question
How much energy does a 100 W electric bulb transfer in 1 minute?
(a) 100 J
(b) 600 J
(c) 3600 J
(d) 6000 J
Advertisements
Solution
(d) 6000 J
Energy transferred, E = power x time = 100 W x 60 s = 6000 J
APPEARS IN
RELATED QUESTIONS
1kWh = …….. J
Calculate the current through a 60 W lamp rated for 250 V. If the line voltage falls to 200 V, how is the power consumed by the bulb affected?
A bulb of 40 W is used for 12.5 h each day for 30 days. Calculate the electrical energy consumed.
A current of 0.2 A flows through a wire whose ends are at a potential difference of 15 V.
calculate:
(i) the resistance of the wire and
(ii) the heat energy produced in 1 minute.
The coil of an electric bulb takes 40 watts to start glowing. If more than 40 W are supplied, 60% of the extra power is converted into light and the remaining into heat. The bulb consumes 100 W at 220 V. Find the percentage drop in the light intensity at a point if the supply voltage changes from 220 V to 200 V.

The diagram above shows a circuit with the key k open. Calculate :
(i) the resistance of the circuit when the key k is open.
(ii) the current drawn from the cell when the key k is open.
(iii) the resistance of the circuit when the key k is closed.
(iv) the current drawn from the cell when the key k is closed.
Name the physical quantity which is measured in kW.
Name three main characteristics of an heating element.
Why is heating element wound on a long porcelain rod in a room heater.
A device is used to transform 12 V a.c. to 200 V a.c. What is the name of this device? Name the principle on which it works.
State the reason why, in a three pin plug, the earth pin is longer and thicker than the other two.
You are required to connect a bulb, a fan and a socket outlet to the mains in one set A and an air-conditioner and a refrigerator to the mains in other set B. Will you recommend the wire of same thickness and same insulation in both? explain your answer.
At what voltage is the electric power generated at the generating station? Explain the transmission of this power to your house.
How can electric energy consumed by an electric appliance be calculated in kilowatt hour (kWh)?
Find the heat produced in joules when a current of 10 amperes flows through a connecting wire of resistance 2 × 10-2 ohms and heating element of resistance 250 ohms for 2 seconds.
The resistance of filament of an electric heater is 500 Ω It is operated at 200V for 1 hour daily. Calculate the current drawn by the heater and the energy consumed in kWh, by the heater in a month of 30 days.
An electric appliance is rated at 1000 W, 250V. Calculate:
(i) The electrical energy consumed by the appliance in 12 hour.
(ii) The cost of energy consumed at Rs. 1.20 per kWh.
How long would this appliance take to use 1 kWh energy when operated at 250 V?
A cooler of 1500 W, 200 volts and a fan of 500 W, 200 volts are to be used from a household supply. The rating of fuse to be used is:
1 mV is equal to:
