Question

a wire is made up of copper who's length is l and cross section radius is r. another wire of length 2l and radius 2r is made up of copper. if the resistence of 1st wire is 2ohm then what is the resistence of 2nd wire

Answer 1

Answer:

1 ohm

area is directly proportional to the square of the radius which means if the radius is increased twice then area will be increased four times so the new area will be 4 r.now by applying the formula of resistance we can find that two in the numerator will divide 4 in the denominator with the quotient 2 which means that the resistance is halved,now 1/2x 2 will be equal to 1.