Electrical power is transmitted over long distances at very high voltage because
Correct answer: B. the current is then small, so the I squared R heating loss in the cables is small
- A. high voltage travels faster
- B. the current is then small, so the I squared R heating loss in the cables is small
- C. high voltage cables are cheaper
- D. consumers need high voltage
Explanation
For a given power, raising the voltage lowers the current in proportion, and since the loss goes as the square of the current, a tenfold rise in voltage cuts the wasted heat a hundredfold. Transformers then step the voltage back down for safe use at the consumer end. This is the main practical reason the grid runs on alternating current.
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About Transformers
Transformers transfer alternating electrical energy between coils by mutual induction, with voltage ratio determined by the turns ratio. The topic covers step-up and step-down transformers, current changes, ideal power conservation and practical losses such as heating and flux leakage. A transformer requires changing magnetic flux, so it does not operate with steady direct current.
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