Question

for two wires of same length and different radii does the resistance of wire change? give reason

Answer 1

The resistance will be different because of radii difference .As the resistance is the difficulty faced in electrons's flow and it's inversely proportional to the diameter or radii. 
The more wider the wire is the less will be the collision of electron with the atoms of the wire so the resistance will also be less.
On the contrary, the less wider wire will result in more resistance to the flow of electrons's. 

Answer 2

it will be different because of the difference in the radii.the more wider the wire is the less will be the collision of electron with the atoms of the wire so the resistance will also be less.

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