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The diagram below shows a circuit containing a lamp L, a voltmeter and an ammeter,. The voltmeter reading 3 V and the ammeter reading is 0.5 A.
What is the resistance of the lamp?
What is the power of the lamp?
Electrical power P is given by the expression P = (Q × V) ÷ time. What do the symbols Q and V represent?
An electric filament lamp is connected to a supply of voltage higher than the recommended value. Give reasons, why compared with a normal performance, the lamp emits a brighter light and its life is shortened.
An electric heater is rated 220 V, 550 W. Electrical energy is also measured in kWh. What do you understand by a kilo-watt-hour?
State the reason why, in a three pin plug, the earth pin is longer and thicker than the other two.
Find the energy released by a current of 0.25 amperes flowing through a heater for 5 minutes. The p.d. is 230 V.
The following table gives the electrical appliances used, their power and the average time for which they are used each day in a home. Estimate the monthly electricity bill if the rate is 60 paise per unit.
| Sr.no. | Name | Nos. | Power rating | Time/day |
| 1 | Bulb | 4 | 100 W | 7.5 hr |
| 2 | Fans | 2 | 50 W | 10 hr |
| 3 | T.V. | 1 | 100 W | 2 hr |
| 4 | Iron | 1 | 500 W | 1 hr |
| 5 | Electric stove | 1 | 750 W | 2 hr |
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:
