Physics
Explain why does a metal wire when connected to a cell offer resistance to the flow of current.
Answer
A metal wire has free electrons which move in a random manner in the absence of any cell connected across it.
When the ends of the wire are connected to a cell, the electrons start moving from the negative terminal of cell to it's positive terminal through the metal wire.
During their movement, they collide with the fixed positive ions and other free electrons of the wire due to which their speed decreases and direction of motion changes.
After each collision, they again accelerate towards the positive terminal and suffer collision with other positive ions and free electrons again. This process continues.
As a result, the electrons do not move in bulk with increasing speeds from one end to the other but they drift towards the positive terminal. This is how a wire offers resistance to the flow of electrons (or current) through it.
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