Question

The temperature of a metal wire rises when an electric current is passed through it because:

• A. collision of conduction electrons with the atoms of metal gives them energy which appears as heat
• B. .when electrons fall from higher energy level to lower energy level, heat energy is released
• C. collisions of metal atoms with each other releases heat energy.
• D. collisions of conduction electrons with each other releases heat energy.

Answer 1

Answer: (A)

collision of conduction electrons with the atoms of metal gives them energy which appears as heat

Answer is A.
A metallic conductor has a large number of free electrons in it. When a potential difference is applied across the ends of a metallic wire, the free electrons begin to drift from the low potential to the high potential region. These electrons collide with the positive ions (the atoms which have lost their electrons). In these collisions, energy of the electrons is transferred to the positive ions and they begin to vibrate more violently. As a result, heat is produced. Greater the number of electrons flowing per second, greater will be the rate of collisions and hence more heat is produced.
Hence, the temperature of a metal wire rises when an electric current is passed through it because collision of conduction electrons with the atoms of metal gives them energy which appears as heat.