Hysteresis in wire extension under tension

Steps:

• Apply tension F to extend wire, following line OS on force-extension graph.
• Reduce F to zero, causing contraction along line PQ, which differs from OS.
• The area between OS and PQ represents energy dissipated as heat due to internal friction.
• Non-coinciding curves indicate incomplete elastic recovery, showing hysteresis.

Why C is correct:

• C depicts the hysteresis loop where unloading curve PQ lies below loading curve OS, per the definition of elastic hysteresis in materials under cyclic loading.

Why the others are wrong:

• A shows reversible elastic behavior with coinciding curves, ignoring energy loss.
• B indicates permanent plastic deformation without contraction path.
• D reverses the loop direction, contradicting the extension then contraction sequence.

Final answer: C