A wire of length L and resistance R is stretched so that its length its doubled. How will
(i) Resistance change (ii) Resistivity change?
Resistance increases 4 times; resistivity remains same
Volume of wire remains same
V=L×A
So if l increases 2 times so the A should decrease 2 times
New L = 2L; New A = A2
R=ρlA
New R= ρ×2×l×2A = 4×ρ×lA = 4 Old R
As ρ is dependent on temp directly so when temperature increases the resistivity increases.
Here ρ remains unchanged as there is no change in temperature.