what are the cause of resistance in a conductor

Asked by bhanu563y | 6th Jan, 2020, 10:35: PM

Expert Answer:

The metal has large number of electrons and equal number of positive ions which do not move while electrons move freely. 
Electrons moves randomly when wire is not connected to cell. They keeps on colliding among themselves and with positive ions. 
When the metal wire is connected to the cell, potential difference is applied across the wire and electrons at negative terminal inside it experience a force towards the direction of positive terminal. 
This force leads to the increase in the speed of electrons and during this movement they collide with fixed positive ions and lose some of the kinetic energy which again leads to the decrease in their speed. 
This leads to the heating up of wire. 
After collision the electrons again get accelerated towards the positive terminal and the process continues. 
Thus, electrons do not move in a bulk with continuously increasing speed but experiences a drift towards the positive terminals. 
Thus, metal wire offers a resistance to flow of electrons flowing through it. 
Hence, resistance in a wire or conductor depends on the number of collisions suffered by the electrons with the positive ions while moving from one end to another end. 

Answered by Shiwani Sawant | 7th Jan, 2020, 11:11: AM