What are the SI units for thermal conductivity?

What are the SI units for thermal conductivity?

• A. Pa*s
• B. W/(m-K)
• C. N/m
• D. J/(kg*K)

Answer: (B)

Thermal conductivity measures how easily heat moves through a material when there’s a temperature difference. In Fourier’s law, heat flux q" (heat transferred per area per time) equals -k times the temperature gradient ∂T/∂x. Here q" has units of watts per square meter (W/m^2) and ∂T/∂x has units of kelvin per meter (K/m). So k = q" / (∂T/∂x) has units (W/m^2) ÷ (K/m) = W/(m·K). This is the SI unit for thermal conductivity, often written as W m^-1 K^-1. It captures how much heat is conducted for a given temperature gradient—the larger k, the better the material conducts heat. For reference, Pa·s is dynamic viscosity (not related to conduction), N/m is surface tension, and J/(kg·K) is specific heat capacity (energy needed to raise a unit mass by 1 K), which are different concepts.

Thermal conductivity measures how easily heat moves through a material when there’s a temperature difference. In Fourier’s law, heat flux q" (heat transferred per area per time) equals -k times the temperature gradient ∂T/∂x. Here q" has units of watts per square meter (W/m^2) and ∂T/∂x has units of kelvin per meter (K/m). So k = q" / (∂T/∂x) has units (W/m^2) ÷ (K/m) = W/(m·K). This is the SI unit for thermal conductivity, often written as W m^-1 K^-1. It captures how much heat is conducted for a given temperature gradient—the larger k, the better the material conducts heat.

For reference, Pa·s is dynamic viscosity (not related to conduction), N/m is surface tension, and J/(kg·K) is specific heat capacity (energy needed to raise a unit mass by 1 K), which are different concepts.