Alternating current, direct current & what is frequency? | Physics | Khan Academy

Current that keeps changing is direction is called alternating current, (AC) whereas the one that never changes its direction is called direct current (DC). Power can be transmitted with low heating losses in the form of AC (not DC). The frequency of the AC in India is 50 Hz. This means the current changes it's direction 100 times per second.

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Created by Mahesh Shenoy

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Edit : unexpected number of likes

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I believe another reason why high voltage / low current A.C is used in power lines is for cost reasons, so that thinner electrical cables (i.e. less copper) can be used.

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[Jo-mzmy]

Transformer can be either step-up or step down. Especially in India, Transformers that we find near our home is step down. It converts high voltage ( usually 11 KV or 1100 Volts ) to low (415 volts). From the transformer three phase lines and one neutral is supplied to electric lines posts. Form that, one phase line and neutral line gives us normal 230 volts .

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