Copper of fixed volume `V` is drawn into wire of length l. When this wire is subjected to a constant force F, the extension produced in the wire is `trianglel`. Which of the following graphs is a straight line?

Options

A. `Delta l "versus" 1//l`
B. `Delta l "versus" 1//l^(2)`
C. `Delta l "versus" 1//l^(2)`
D. `Delta l "versus" l`

Answer

B

Explanation

As V= Al ..(i)
where A is the area of cross-section of the wire.
Young.s modulus `Y= ((F//A))/((Delta l//l)) = (Fl)/(A Delta l)`
`Delta l= (Fl)/(YA) = (Fl^(2))/(YV)` (Using (i))
`Delta l prop l^(2)`
Hence, the graph between `Delta l adn l^(2)` is a straight line