When load is applied to a wire the extension is 3 mm, the extension in the wire of same material, length but half the radius by the same load is :

Options

A. 0.75 mm
B. 6 mm
C. 1.5 mm
D. 12.0 mm

Answer

D

Explanation

`Deltal=(FL)/(Ay)rArr1lprop1/A`
or `Deltalprop1/(r^(2))`
`therefore(Deltal_(2))/(Deltal_(1))=(r_(1)^(2))/(r_(2)^(2))=(2/1)^(2)=4`
`rArrDeltal_(2)=4Deltal_(1)=4xx3=12mm`
So, the correct choice is (d).