Question

Uniform wire is stretched uniformly by 0.5% its resistance changes by what

Answer 1

When wire is stretched then volume of wire doesn't change .
We know, R = ρL/A
Here, R is resistance , ρ is resistivity , L is the length of wire and A is base area of wire.
volume of wire , V = AL [ volume = base area × length ]
so, R = ρL²/V
R is directly proportional to L² [ ∵ ρ and V are constant ]
in case of finding error ,
∆R/R = 2∆L/L
so, % error in R = 2 × % error in L
% error in R = 2 × 0.5 % = 1 %

Hence, answer is 1%

Answer 2

Explanation:

R'/R =2L%

R'= (0.5x2)%

R' = 1%