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प्रश्न
What is electric power? State and define its S.I. unit.
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उत्तर
Electric power is the rate of doing work or it is the work done in 1 second.
The S. I. unit of power is ‘Watt’.
If a current of 1 ampere flows through a metallic conductor at a potential difference of 1 volt, the power is said to be 1 watt.
or 1 Watt = 1 Volt × 1 Ampere.
संबंधित प्रश्न
Name the commercial unit of electric energy.
How many joules are there in one kilowatt-hour?
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.
Write the SI units for:
(a) Electric current
(b) Potential difference
(c) Charge.
The diagram 31 shows a 3 terminal plug socket.
(i) What is the purpose of the terminal E?
(ii) To which part of the appliance is the terminal E connected?
(iii) To which wire L or N, is the fuse connected and why?
Define electric power. An electrical device of resistance R is connected across a source of voltage V and draws a current I. Derive an expression for power in terms of current and resistance.
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An Electric bulb is marked 100 W, 230 V. What how long would this lamp take to consume one unit of electricity?
A family uses 8 kW of power. Direct solar energy is incident on the horizontal surface at an average rate of 200 W per square meter. If 20% of this energy can be converted to useful electrical energy, how large an area is needed to supply 8 kW?
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.
