If the length of a wire is doubled while keeping its material and cross-sectional area same, the resistance of the wire
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → becomes double of its initial value
The resistance of a wire is \( R = \rho L/A \). With the material (\( \rho \)) and the area \( A \) unchanged, \( R \propto L \).
\( \displaystyle R' = \frac{\rho (2L)}{A} = 2R \)
The resistance becomes double.
NCERT (2026-27):
Ohm’s Law – “… Thus, doubling the length of a conductor doubles the resistance. In general, then resistance is proportional to length,
\( \displaystyle R \propto l \qquad (3.5) \)”
Ohm’s Law – “… where the constant of proportionality ρ depends on the material of the conductor but not on its dimensions.”