Young's modulus of a metallic wire — NEET & JEE Questions

Question 1 · difficulty L1 · recall

Young's modulus is defined as

• A. strain divided by stress
• B. force divided by length only
• C. longitudinal stress divided by longitudinal strain within the elastic limit
• D. extension divided by area

Question 2 · difficulty L1 · understanding

The SI unit of Young's modulus is

• A. metre
• B. newton only
• C. joule per second
• D. pascal

Question 3 · difficulty L2 · understanding

For a wire of length L, area A and extension ΔL under force F, Young's modulus is

• A. FL/(AΔL)
• B. FΔL/(AL)
• C. AFL/ΔL
• D. F/(LΔL)

Question 4 · difficulty L2 · application

If the same force is applied to two wires of the same material and length, the thicker wire extends

• A. more
• B. less
• C. the same amount
• D. an amount independent of area

Question 5 · difficulty L2 · understanding

Young's modulus of a wire is defined as the ratio of

• A. longitudinal stress to longitudinal strain
• B. longitudinal strain to longitudinal stress
• C. force to extension
• D. extension to original length only

Question 6 · difficulty L3 · application

If wire length doubles with force, area and material unchanged, extension

• A. halves
• B. quadruples
• C. doubles
• D. stays unchanged

Question 7 · difficulty L3 · application

A wire has radius r. If radius doubles at fixed F, L and Y, extension becomes

• A. one-half
• B. twice
• C. four times
• D. one-fourth

Question 8 · difficulty L3 · application

For the same wire within its elastic limit, if the applied force is doubled, its extension will approximately

• A. double
• B. halve
• C. remain unchanged
• D. become four times

Question 9 · difficulty L3 · application

In an experiment, a wire of length 1.5 m and cross-sectional area 2.0 mm$^2$ extends by 0.30 mm when a load of 8.0 kg is hung from it (take g = 10 m s$^{-2}$). The Young's modulus of the material is

• A. 2.0 x 10$^{10}$ N m$^{-2}$
• B. 2.0 x 10$^{11}$ N m$^{-2}$
• C. 4.0 x 10$^{11}$ N m$^{-2}$
• D. 1.0 x 10$^{11}$ N m$^{-2}$

Question 10 · difficulty L4 · analysis

Why should loads be added gradually in a Young's modulus experiment?

• A. To avoid shocks and help keep deformation within the elastic limit
• B. To change the material's Young's modulus deliberately
• C. To make wire area increase without bound
• D. To eliminate gravity