Question

The resistance of a wire is 12 ohm . its length l and area a. What will be the new resistance of the length of the wire is stretched to double of it's original length.

Answer 1

Hi

R = 12 ohms

R = rho x (length/area)

rho is the resistivity , as same material is used resistivity remains the same.

let R' be new resistance

R' = rho x (2length / (area/2)) , As volume is constant if it is drawn area will also decrease proportionally.

∴ R' = rho x 4(length/area)

→ R' = 4 (R) , ∵ R = rho x (length/area)

→  R ' = 4x12 = 48Ω

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