Advertisements
Advertisements
प्रश्न
An electric bulb is rated 220 V and 100 W. When it is operated on 110 V, the power consumed will be ______.
पर्याय
100 W
75 W
50 W
25 W
Advertisements
उत्तर
An electric bulb is rated 220 V and 100 W. When it is operated on 110 V, the power consumed will be 25 W.
Explanation:
Resistance of the bulb
∴ P = `"V"^2/"R"`
R = `"V"^2/"P"`
= `(220 "V"^2)/100`
= 484 Ω
Then, Power consumed at 110 V
P' = `("V'")^2/"R"`
= `(110 "V"^2)/484`
= 25 W
APPEARS IN
संबंधित प्रश्न
If a bulb of 60W is connected across a source of 220V, find the current drawn by it.
Define watt-hour. How many joules are equal to 1 watt-hour?
An immersion heater rated 1000 W, 220 V is used to heat 0.01 m3 of water. Assuming that the power is supplied at 220 V and 60% of the power supplied is used to heat the water, how long will it take to increase the temperature of the water from 15°C to 40°C?
What is the current in the circuit shown (Fig. )
What is the energy conversion when an electric current passes through a metallic wire?
What is electric power? State and define its S.I. unit.
Name two common material used for heating elements.
Give two precautious that you would take while putting off an electric switch.
State the reason why, in a three pin plug, the earth pin is longer and thicker than the other two.
An electric bulb is rated 240V-60W and is working at 100% efficiency.
(i) Calculate the resistance of bulb.
(ii) (a) Draw the circuit diagram.
(b) What is the rate of conversion of energy in each bulb?
(c) Total power used by the bulbs.
An electric bulb is rated as 100W – 250V. What information does it convey? Calculate the current through the filament of the bulb.
Two resistances R1 = 4Ω and R2 = 6Ω are connected in series. The combination is connected with a battery of e.m.f. 6V and negligible resistance. Calculate:
(i) the heat produced per minute in each resistor,
(ii) the power supplied by the battery.
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 joule.
The average work done by a human heart while it beats once is 0.5 Joule. The power used by heart if it beats 72 times in a minute:
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.
