The resistance of the wire is given as, R=Aρl
Therefore, ρ=RlA
ρ=Rl(πr2)
For percentage error, we can write ρΔρ=RΔR+2rΔr+lΔl
ρΔρ×100=RΔR×100+2rΔr×100+lΔl×100
=(10010+2×0.350.05+150.2)×100
=(101+72+751)×100
Hence, ρΔρ=39.9
JEE Main 2024 — Physics Mechanics
The radius (r), length (l) and resistance (R) of a metal wire was measured in the laboratory as
r=(0.35±0.05)cm, R=(100±10)ohm, l=(15±0.2)cm
The percentage error in resistivity of the material of the wire is :
Held on 1 Feb 2024 · Verified 6 Jul 2026.
25.6
39.9
37.3
35.6
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