Exams › JEE Main › Physics

A cylindrical wire is stretched so that its length becomes twice the original value. Because of the resulting reduction in its diameter, what is the percentage increase in its resistance?

1. 200%
2. 100%
3. 50%
4. 300%

Correct answer: 300%

Solution

When the length of the wire is doubled, its resistance increases due to the lengthening effect, while the diameter reduction leads to a decrease in cross-sectional area, further increasing resistance. The combined effect results in a total resistance increase of 300%.

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 →