What does conductivity refer to in physical properties?

Conductivity refers specifically to the ability of a material to allow the flow of heat and electricity. This property is critical in various applications, such as in electrical wiring, electronic components, and thermal management systems. Materials that are good conductors, like metals, enable electrons to move freely, facilitating the efficient transmission of electric current. Similarly, conductive materials efficiently transfer heat, making them ideal for applications where heat dissipation is necessary, such as in cooking utensils or heat sinks.

In contrast, other options present different physical properties: the ability to change a solid to a liquid pertains to melting; restricting heat and electricity flow describes insulating materials; and the ability to reflect light relates to optical properties. These descriptions do not capture the essence of conductivity, which is fundamentally focused on the ability to transmit energy in the form of electricity or thermal energy.