A fixed volume of iron is drawn into a wire of length `l`. The extension produced in this wire by a constant force F is proportional to

Copper of fixed volume V is drawn into a wire of length l. When this wire is subjected to a constant force F, the extension produced in the wire is Deltal . If Y represents the Young's modulus, then which of the following graphs is a straight line?

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