The following four wires of length L and radius r are made of the same material .Which of these will have the largest extension,when the same tension is applied?

Options

A. L= 100cm, r=0.2mm
B. L=200cm, r=0.4mm
C. L=300cm,r=0.6mm
D. L=400cm,r=0.8mm.

Answer

A

Explanation

`Y=F/A L/(Deltal)rArrDeltal=(FL)/(YA)`
Since Y and F is same
`thereforeDeltalpropL/A` or `DeltalpropL/(r^(2))`
`L/(r^(2))` is maximum when L = 100 cm and r = 0·02 mm So correct choice is (a).