Material and Temperature

Resistance also depends on the material and its temperature.

Different substances have different resistivities. A low-resistivity material such as copper conducts current well. A higher-resistivity material opposes current more strongly for the same dimensions.

For most metals: **temperature increases → resistance increases Heating makes the metal lattice vibrate more strongly, increasing collisions that impede electron drift. Over a suitable temperature range: R = R₀[1 + α(T − T₀)]** where `α` is the temperature coefficient of resistance.

Some materials, particularly semiconductors, behave differently. Their resistance can decrease significantly as temperature rises because more mobile charge carriers become available.