Question

A wire of resistance R is further extended to twice of its length. find the ratio of initial resistance to equal resistance.​

Answer 1

Answer:

R = density × length / Area

Here density constant in both cases...

so that

Volume of 1st = volume of 2nd

Area(A1) × length (L1) = Area (A2) × length (L2)

suppose

A1 = A and L1 = L and A2 = A' and L2 = 2×L

A × L = A' × 2×L

A' = A/2

R/R' = density × L × A / density × 2L × A × 2

R/R' = 1/4