Question

A THICK WIRE IS STRETCHED SO THAT ITS LENGTH BECOMES TWO TIMES. ASSUMING THERE IS NO CHANGE IN ITS DENSITY THEN WHAT IS THE RATIO OF CHANGE IN RESISTANCE OF THE WIRE TO THE INITIAL RESISTANCE OF THE WIRE?

Answer 1

Answer:

Resistance of the wire is given by

R=ρA1=ρ(Al)l2=Vρl2   (∵Al=V)

So, R∝l2  (If density remains same)

or  RR′=4R

Hence, change in resistance =4R−R=3R

Therefore, original resistancechange in resistance=R3R=3:1