Question

a uniform wire of resistance 100 ohm metre is melted and recast into wire of length double that of the original. what would be the resistance of the wire formed

Answer 1

Volume will be same anyways. So (area*length) will be same in what ever shape u redraw it into. a1*l1=a2*l2. So u get new length of 2*l1 and area to be of a1/2. So the new resistance is 4*(that of the old resistance) =400

Answer 2

The resistance R is directly proportional to the length l. Therefore, the resistance will be doubled.So,new resistance will be 200 ohm