Advertisements
Advertisements
प्रश्न
Two lamps are rated 220V, 50W and the other rated 220V, 100W are connected in series with the mains of 220 V. Explain, why the 50W lamp glows more?
Advertisements
उत्तर
From relation R = V2/P, the resistance of filament of 50W lamp will be more than that of 100W lamp. If the two lamps are connected in series with the mains, same current will flow through each lamp. From relation H = I2Rt, since resistance of 50W lamp is more than that of 100W lamp, so the 50 W lamp will consume more electrical energy than that of 100W lamp, in the same time. Hence the 50W lamp will glow more.
संबंधित प्रश्न
Electrical power P is given by the expression P = (Q × V) ÷ time. What do the symbols Q and V represent?
A current of 2 A is passed through a coil of resistance 75Ω for 2 minutes. (a) How much heat energy is produced? (b) How much charge is passed through the resistance?
What is electric power? State and define its S.I. unit.
An electric current is passed through a metallic wire. The wire gets heated up. Give the reason. Is it possible to melt the wire by passing a heavy current?
What would happen and why, to an electric bulb when it is connected across a supply of voltage (i) lower (ii) higher than its proper rating?
State (i) the S. I. unit, (ii) the household unit, of electrical energy. How are these units related?
Find the energy released by a current of 0.25 amperes flowing through a heater for 5 minutes. The p.d. is 230 V.
An Electric bulb is marked 100 W, 230 V. What current does it take?
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 |
An overhead tank of capacity 10 k litre is kept at the top of building 15 m high. Water falls in tank with speed 5`sqrt2` m/s. Water level is at a depth 5 m below ground. The tank is to be filled in `1/2` hr. If efficiency of pump is 67.5% electric power used is ______ W.
