Exams › JEE Main › Physics

Young’s moduli of the material of wires A and B are in the ratio of 1: 4, while its area of cross sections are in the ratio of 1: 3. If the same amount of load is applied to both the wires, the amount of elongation produced in the wires A and B will be in the ratio of - [Assume length of wires A and B are same]

1. 12: 1
2. 1: 36
3. 36: 1
4. 1: 12

Correct answer: 12: 1

Solution

The elongation of a wire is inversely proportional to its Young's modulus and directly proportional to its length and the applied load, while also being inversely proportional to its cross-sectional area. Given the ratios of Young's moduli (1:4) and cross-sectional areas (1:3), we can derive the elongation ratio as follows: elongation is proportional to the load divided by the product of Young's modulus and area. This results in a ratio of elongation for wires A and B of 12:1.

Related JEE Main Physics questions

• Select the incorrect statement.
• A steel wire has length l and cross-sectional area A. When a certain load is applied, it elongates by 1 cm. If the same load is now applied to another steel wire made of the same material, having twice the length and half the cross-sectional area, what will be its extension?
• For common metals such as aluminium and copper, which sequence correctly represents the relative magnitudes of the elastic moduli?
• A steel sheet fails under a shear stress of 3.5 × 10⁸ N m⁻². The approximate force required to punch a circular hole of diameter 1 cm through a steel plate 0.3 cm thick is:
• A copper wire of fixed volume V is stretched out to a length l. If a constant force F is applied to this wire and it elongates by Δl, which of the following plots would be a straight line?
• A material has Poisson’s ratio equal to 0.5. When a tensile force is applied to a wire made of this material, its cross-sectional area decreases by 4%. The corresponding percentage increase in its length is:

⚔️ Practice JEE Main Physics free + battle 1v1 →