The following four wires are made of the same material which of these will have the largest extension when the same tension is applied

Options

A. Length =50 cm, diameter =0.5 mm
B. Length =100 cm, diameter =1 mm
C. Length =200 cm, diameter =2 mm
D. Length =300 cm, diameter =3 mm

Answer

A

Explanation

(a) `DeltaL=(FL)/(AY)`
or `DeltaL prop (L)/(d^(2)) " "[because A=(pid^(2))/(4)]`
Therefore, `DeltaL` will be maximum for that wire for which `(L)/(d^(2))` is maximum.