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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
An electric motor takes 5 A from a 220 V line. Determine the power of the motor and the energy consumed in 2 h.
If a bulb of 60W is connected across a source of 220V, find the current drawn by it.
Which one has a higher electrical resistance : a 100 watt bulb or a 60 watt bulb?
Define watt-hour. How many joules are equal to 1 watt-hour?
A 2 kWh heater, a 200 W TV and three 100 W lamps are all switched on from 6 p.m. to 10 p.m. What is the total cost at Rs 5.50 per kWh?
Explain why, filament type electric bulbs are not power efficient.
Distinguish between kilowatt and kilowatt-hour.
An electric bulb is rated ‘100 W, 250 V’. How much current will the bulb draw if connected to a 250 V supply?
A bulb of 40 W is used for 12.5 h each day for 30 days. Calculate the electrical energy consumed.
Two bulbs are rated 60 W, 220 V and 60 W, 110 V respectively. Calculate the ratio of their
resistances
Water in an electric kettle connected to a 220 V supply took 5 minutes to reach its boiling point. How long would it have taken if the supply voltage had fallen to 200 V?
An electric toaster draws 8 A current in a 220 V circuit. It is used for 2 h. Find the cost of
operating the toaster if the cost of electrical energy is Rs. 4.50 per kWh.
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.
A resistor of resistance R is connected to an ideal battery. If the value of R is decreased, the power dissipated in the resistor will ______________ .
A simple electric circuit has 24 V battery and a resistor of 60 Ω. What will be the current in the circuit? The resistance of the connecting wires is negligible.
What is electric power? State and define its S.I. unit.
Why is heating element wound on a long porcelain rod in a room heater.
State the position of heating element with respect to principal focus of concave reflector and give reason for choosing this position.
Why is the heating element of an electric oven wound on a helix? State the reason.
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?
State two advantages of filling an inert gas in an evacuated electric filament lamp.
How does the heat produced by die passage of current in a metallic wire depend on the resistance of the wire.
How is the amount of heat produced calculated due to the passage of current in a metallic conductor? Derive an expression for it.
Three 250 W heaters are connected in parallel to a 100 V supply, Calculate total current taken from the supply.
State other bigger units of electric power and express them in watt.
How can electric energy consumed by an electric appliance be calculated in kilowatt hour (kWh)?
An Electric bulb is marked 100 W, 230 V. What how long would this lamp take to consume one unit of electricity?
A house is provided with 15 bulbs of 40W, 5 bulbs of 100W, 5 fans of 80 W, and one heater of 1.0 kW. Each day bulbs are used for 4h, fans for lOh, and heater for 2h. The voltage of mains is 220 V. Calculate:
(i) Maximum power of the circuit in the house,
(ii) maximum current capacity of the main fuse in the house,
(iii) the electrical energy consumed in a week,
(iv) cost of electricity consumed at 1.25 Rs. per kWh.
Unit of electric power may also be expressed as:
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
A room has AC run for 5 hours a day at a voltage of 220V. The wiring of the room consists of Cu of 1 mm radius and a length of 10 m. Power consumption per day is 10 commercial units. What fraction of it goes in the joule heating in wires? What would happen if the wiring is made of aluminium of the same dimensions?
`[ρ_(Cu) = 1.7 xx 10_(Ωm)^-8, ρ_(Al) = 2.7 xx 10^-8 Ωm]`
A conductor of 10 Ω is connected across a 6 V ideal source. The power supplied by the source to the conductor is ______.
