How does temperature typically affect the resistance of metals?

How does temperature typically affect the resistance of metals?

• A. Resistance usually increases with temperature.
• B. Resistance usually decreases with temperature.
• C. Temperature has no effect on resistance.
• D. Resistance only changes with pressure.

Answer: (A)

When temperature rises, atoms in a metal vibrate more strongly, which causes conduction electrons to scatter more as they move through the lattice. This extra scattering makes it harder for electrons to flow, so the metal’s resistivity increases. Since resistance R in a wire is proportional to resistivity (R = ρL/A), heating a metal increases its resistance. For most metals, this change is roughly linear over common temperature ranges and is described by a positive temperature coefficient of resistance: a small rise in temperature leads to a small rise in resistance. For example, copper’s resistance increases with temperature because its α value is positive. In contrast, this isn’t how metals behave at very low temperatures or in all materials—some materials may behave differently, but the typical metal response is an increase in resistance with temperature.

When temperature rises, atoms in a metal vibrate more strongly, which causes conduction electrons to scatter more as they move through the lattice. This extra scattering makes it harder for electrons to flow, so the metal’s resistivity increases. Since resistance R in a wire is proportional to resistivity (R = ρL/A), heating a metal increases its resistance. For most metals, this change is roughly linear over common temperature ranges and is described by a positive temperature coefficient of resistance: a small rise in temperature leads to a small rise in resistance. For example, copper’s resistance increases with temperature because its α value is positive. In contrast, this isn’t how metals behave at very low temperatures or in all materials—some materials may behave differently, but the typical metal response is an increase in resistance with temperature.