Thermal Resistance
Thermal analog of electrical resistance. ΔT = P × R_th.
Variables
Derivation
From P = kAΔT/L, define R_th = L/(kA) so ΔT = P·R_th. Resistances add in series.
Your notes
Check value
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- L = 2 m (Length)
- k = 3 W/(m·K) (Thermal conductivity)
- A = 4 m² (Cross-sectional area)
Result: Rth = 0.16666667 K/W
Other formulas with the same quantities
- Drag Force (Mechanics, Dynamics) shares Cross-sectional area
- Terminal Velocity (Mechanics, Dynamics) shares Cross-sectional area
- Resistance (Electricity & Magnetism, Electric Circuits) shares Cross-sectional area
Where this formula is listed
- Thermodynamics formulas, under Heat & Temperature, alongside Heat Capacity, Latent Heat, Linear Thermal Expansion, Volume Thermal Expansion and Stefan-Boltzmann Law.
- In the thermodynamics list it comes after Stefan-Boltzmann Law and before Newton's Law of Cooling.
- Thermodynamics formula sheet, one of 34 formulas printed with symbol keys and SI units.
- The full formula index, grouped by category and topic.
Common questions
What is the Thermal Resistance formula?
Thermal Resistance is written R_th = L/(kA). Thermal analog of electrical resistance. ΔT = P × R_th. It belongs to Thermodynamics, under Heat & Temperature.
What are the units in R_th = L/(kA)?
In SI units, R_t h is thermal resistance, measured in s³·K/(kg·m²); L is length, measured in m; k is thermal conductivity, measured in kg·m/(s³·K); A is cross-sectional area, measured in m².
How is the Thermal Resistance formula derived?
From P = kAΔT/L, define R_th = L/(kA) so ΔT = P·R_th. Resistances add in series. The result is R_th = L/(kA).