Physics · Class 10

Electric Power and the Heating Effect of Current

Electric current flowing through a conductor generates heat. This heating effect is used in electric bulbs, toasters, heaters, and many other applianc

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Why do high-tension power cables not get very hot even though they carry large currents?

High-tension lines use very high voltage and very low current to transmit power, because power = voltage times current. Low current means little heating according to Joule's Law since heat is proportional to current squared. Once the voltage is stepped down, the current increases but the distance traveled is short.

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Why is a fuse wire made of a material with high resistance?

High resistance means more heat is produced for the same current. The fuse wire is designed to melt at a specific temperature. When current exceeds the safe limit, the high resistance of the fuse wire generates enough heat to melt it quickly, breaking the circuit and protecting the device from damage.

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How is an electric bulb more efficient than an incandescent bulb?

LED bulbs convert much more of the electrical energy into visible light and less into waste heat. Incandescent bulbs waste about 95 percent of energy as heat. LEDs waste much less, making them more efficient and using less electricity for the same brightness.

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