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प्रश्न
What is meant by "electric power"?
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उत्तर
The energy required per unit of time is called electrical power.
संबंधित प्रश्न
Define Electric power.
What determines the rate at which energy is delivered by a current?
An electric bulb is rated at 220 V, 100 W. What is its resistance?
Write the formula for electric power in terms of potential difference and current.
An electric kettle for use on a 230 V supply is rated 3000 W. For safe working, the cable connected to it should be able to carry at least:
(a) 2 A
(b) 5 A
(c) 10 A
(d) 15 A
How many joules of electrical energy are transferred per second by a 6 V; 0.5 A lamp?
(a) 30 J/s
(b) 12 J/s
(c) 0.83 J/s
(d) 3 J/s
Name two gases which are filled in filament type electric light bulbs.
Explain why, filament type electric bulbs are not power efficient.
1Kwh =`( 1 "volt "xx 1 am pere xx.............)/1000`
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?
An electric kettle is rated 2.5 kW, 250 V. Find the cost of running the kettle for two hours at Rs. 5.40 per unit.
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.
Define 1 kilowatt hour.
The diagram shows a coil connected to a center zero galvanometerG . The galvanometer shows a deflect ion to the right when the north pole N of a powerful magnet is moved to the right as shown .
(i) Explain, why the defelct ion occurs in the galvanometer.
(ii ) State whether th e current in the coil is cl ockwise or anticl ockwise
when viewed from the end P.
(iii ) State th e observation in G when the coil is moved away from north
pole N of the magnet keeping the magnet stationary.
(iv)State the observation in G when both the coil and the magnet are
moved to right at th e same speed .
What are the two main systems of wiring commonly used in houses? Which of these systems mentioned by you is better and why?
Name three main characteristics of an heating element.
Name two common material used for heating elements.
Why is the heating element of an electric oven wound on a helix? State the reason.
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?
Of the three connecting wires in a household circuit: Which two of the three wires are at the same potential? In which of the three wires should the switch be connected?
If the rating of an electric bulb is 100W – 230V, Explain its meaning.
Two electric lamps each rating 100 W, 110 V are connected in series to a 220 V power supply and two other electric lamps each of marking 100 W, 220 V are connected in parallel to the same power supply. Will anyone of the two combinations give more light than the other? Give a reason for your answer.
What is the function of the split rings in a d.c. motor?
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?
At what voltage is the electric power generated at the generating station? Explain the transmission of this power to your house.
State (i) the S. I. unit, (ii) the household unit, of electrical energy. How are these units related?
I ampere of current is passed through a resistor of resistance R ohm for time t second. Obtain expression for
(i) the electrical energy, and
(ii) the electrical power spent.
An electric iron is rated at 230 V, 750 W. What is its resistance? What maximum current can be passed through it?
An electric bulb is rated as 100W – 250V. What information does it convey? Calculate the current through the filament of the bulb.
Two bulbs are rated: bulb A 100W, 120 V bulb B 10W, 120 V. If both are connected across a 120V supply, which bulb will consume more energy, When in series? Also calculate the current through each bulb in above cases.
An electrical appliance is rated 1500 W, 250 V. This appliance is connected to 250 V mains. Calculate:
(i) the current drawn,
(ii) the electrical energy consumed in 60 hours,
(iii) the cost of electrical energy consumed at Rs. 2.50 per kWh.
What is the commercial unit of electrical energy?
What is the commercial unit of electrical energy? Represent it in terms of joules.
If a heater coil rated lkW, 220 V is connected in series with an electric bulb of 100 W, 220 V and are supplied 200V, power consumed by the bulb in this circuit is ______.
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:
A electric bulb is rate 220 V, 60 W. its electric cell resistance is nearly
