If a wire conductor of 0.2 ohm resistance is doubled in length, its resistance becomes

Answer: Option C

Resistance (R) of a wire is directly proportional to its length (L) and inversely proportional to its cross-sectional area (A). This relationship is given by: R = ρL/A, where ρ (rho) is the resistivity of the material.

When the length of the wire is doubled, the new length becomes 2L. However, if the wire's volume remains the same (which is generally assumed when we stretch a wire), doubling the length reduces the cross-sectional area to half (A/2). Think of it like stretching dough - it gets longer but thinner.

So, the new resistance (R') will be: R' = ρ(2L) / (A/2) = 4ρL/A.

Since the original resistance R = ρL/A, we can say that R' = 4R.

Therefore, if the original resistance was 0.2 ohm, the new resistance becomes: R' = 4 × 0.2 = 0.8 ohm.

Final Answer: 0.8 ohm