The resistance of a metal increases with temperature.

• A. Increases with temperature
• B. Decreases with temperature
• C. Remains constant
• D. Varies randomly

Answer: (A)

Metallic resistance changes with temperature because the metal's atoms vibrate more at higher temperatures, which makes it harder for free electrons to move. As temperature rises, lattice vibrations (phonons) scatter electrons more, so the resistivity increases. For many metals, this relationship is roughly linear over a moderate range and can be written as R ≈ R0[1 + αΔT], where α is a positive constant. That means the resistance increases when the temperature goes up.

So the statement that resistance increases with temperature best fits how metals behave. A decrease would require a negative temperature coefficient, which doesn’t apply to metals in general. Remaining constant would imply no change with temperature, which isn’t correct for metals, and varying randomly would ignore the physical mechanism that links temperature to electron scattering.