Asked Dec 27, 2019

Why does a wire that carries electric current becomes hot?


Expert Answer

Step 1

The heating effect in a wire due to electric current is a consequence of Joule’s law of Heating.

According to this law, the total amount of heat that is generated in a conducting wire carrying current, is directly proportional to the square of the amount of current passing through the wire when the resistance of the wire and the time of flow of current through the wire are taken as constants.

Mathematically it is expressed as,

Physics homework question answer, step 1, image 1
Step 2

Here H is the heat generated due to heating, i is the current flowing through the wire .Here the resistance R and the time of flow of current t are taken to be constants.

If R and t are also changing along with the current i, then the law is expressed as,

Physics homework question answer, step 2, image 1
Step 3

Here J is the Joule’s constant.

Current in an electrical circuit is governed by the flow of electrons inside the wire. These electrons...

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