What happens to wire resistance when the temperature rises by 10 degrees Celsius?

• A. Increases by 10%
• B. Decreases by 10%
• C. Remains the same
• D. Increases by 5%

Answer: (B)

When temperature increases, the atoms in a metal vibrate more, which makes it harder for electrons to move and raises the metal’s resistivity. The resistance of a wire follows R = R0[1 + α(T − T0)], where α is a positive temperature coefficient for metals. So a rise of 10°C leads to a higher resistance, not lower.

For many metals, a 10°C rise translates to about a 3–4% increase in resistance (for copper, roughly 3.9%). Among the given options, the one stating that resistance increases by about 5% is the closest and best reflection of this behavior. The other choices—decreasing, remaining the same, or increasing by 10%—do not match how metal resistance typically responds to temperature.