2022 · Q28
A metal wire of length l and diameter d has a resistance R. What would be the resistance of another wire of the same metal and of same length but having double the diameter ?
General KnowledgePhysics
- AR
- BR/4
- CR/2
- D2R
Explanation
Resistance R = rho*l/A, where A = pi*d^2/4. Doubling the diameter increases the cross-sectional area fourfold while length and resistivity stay the same. The resistance therefore falls to one-fourth. Hence the new resistance is R/4.