A1.
Power loss in any transmission line= I^2 R.
So, there is appreciable loss of power when large current is transmitted.
As we know power transmitted=VI.
So by increasing voltage same amount of power can be transmitted at lower currents thus causing lower power loss.
This increasing decreasing of voltage is possible only in AC with the help of transformers.
So ac is being used for transmission.
Although high voltages have disadvantages too
1.increased insultaion required.
2. increased difficulty in safe handling.
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Q2.Explain power rating of a bulb?
A1. Lightbulb come with the rating say 240 V, 60 W.
It means if you connect 240V across the bulb ,the energy converted is at the rate of 60 W.
If Voltage <240v>it will be dimmer
If Voltage>240V it will probably burnout.
=>240V is the operating voltage at which bulb is designed to work.
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Q3.Why is the earth pin in a 3 pin plug the longest and the thickest?
A3. Generally the current at the time of fault is 5 to 10 times more than the normal current .Hence the earth pin is thicker than the other two pins.
It is longer,so that it is the first to make connection and last to disconnect, assuring safety for the person using the equipment.
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Done for the day....
Cheers...
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