Q25 of 72 Page 12

What is the S.I. unit of Power?

The S. I. of Power is Watt, which is denoted by the letter W. The power of 1 watt is a rate of working of 1 joule per second. That is, 1 watt = .

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23 An electric bulb is rated at 220V, 200W. What is its resistance? 24 A torch bulb is rated at 2.5V, 500 A. Find the power and resistance. 26 A heater coil connected to a 220 V ha a resistance of 150Ω . How long will it take for this coil to heat 1 kg of water from 20o C to 60o C, assuming that all the heat is taken up by the water? 27 How much current will an electric heater draw from a 220 volt line if the resistance of the heater is 44 ohms?