What measures the heat transfer capability through a substance by conduction?

The measure of heat transfer capability through a substance by conduction is known as thermal conductivity. It quantifies how well a material can transfer heat. Materials with high thermal conductivity, like metals, allow heat to pass through them quickly, whereas materials with low thermal conductivity, such as wood or plastic, insulate against heat flow.

Thermal resistivity, while related to the concept of heat transfer, specifically refers to a material's opposition to heat flow. It is the reciprocal of thermal conductivity; thus, understanding it in terms of heat transfer capability means recognizing that lower resistivity indicates better conductivity. This makes thermal conductivity the more direct measure for assessing how well a substance transfers heat.

Thermal capacity, often confused with thermal conductivity, describes a material's ability to store heat rather than its ability to conduct it. Similarly, thermal expansion refers to how materials change dimensions in response to temperature changes. These terms, while they involve heat, do not directly measure the capability for heat transfer through conduction in the same way thermal conductivity does.