Q. A wire of a certain material is stretched slowly by ten per cent. Its new resistance and specific resistance become respectively
A) 1.1 times, 1.1 times
B) 1.2 times, 1.1 times
C) 1.21 times, same
D) Both remain the same
Explanation
[Solution from source] The volume stays constant, so R = ρl/A = ρl²/V is proportional to l². A 10% stretch gives R' = (1.1)²R = 1.21R. Specific resistance (resistivity) depends only on the material and temperature, so it stays the same. Answer (3).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.