The resistance of a wire is 10 ohm. If it is stretched to double its length, its new resistance will be?
Q1. The resistance of a wire is 10 ohm. If it is stretched to double its length, its new resistance will be?
Answer: 40 ohm
Explanation: Resistance is directly proportional to length and inversely proportional to area. When length doubles, area halves, so R = ρ(2l)/(A/2) = 4ρl/A = 4R.