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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
Define watt. Write down an equation linking watts, volts and amperes.
In a filament type light bulb, most of the electric power consumed appears as:
(a) visible light
(b) infra-red-rays
(c) ultraviolet rays
(d) fluorescent light
List the names of three electrical gadgets used in your house. Write their power, voltage rating and approximate time for which each one is used in a day. Hence, find the electrical energy consumed by each in a day.
Calculate the current through a 60 W lamp rated for 250 V. If the line voltage falls to 200 V, how is the power consumed by the bulb affected?
Two bulbs are rated 60 W, 220 V and 60 W, 110 V respectively. Calculate the ratio of their
resistances
What is the current in the circuit shown (Fig. )
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.
An electric appliance is rated at 1000 W, 250V. Calculate:
(i) The electrical energy consumed by the appliance in 12 hour.
(ii) The cost of energy consumed at Rs. 1.20 per kWh.
How long would this appliance take to use 1 kWh energy when operated at 250 V?
