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unit of measure: the base unit | the supplementary unit | the derived unit

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Thermal resistance


The thermal resistance is the physical measure, which defines the body or environment characteristic, inverse to the heat transfer coefficient, which characterizes the ability to prevent (internal) heat transfer at molecular level.

1 kelvin per watt is the thermal resistance of the body or the environment, equally to the thermal stress, necessary for heat flux transporting equivalent to 1 watt per square meter by 1 meter square surface at the difference (change) of its temperature of 1 kelvin.

1 kelvin per watt is the thermal resistance, for which an amount of 1 joule heat that it scroll for 1 second results in the temperature difference across the material of 1 kelvin.


system of units:   SI;
statute:   derived unit;
name the value:   R;
unit name:   kelvin per watt;
symbol unit:   K/W;
relationship of definition:   R = Е/P;
dimension:   M-1 L-2 T3 Θ;
expression in other units:   °F·h/BtuIT, °F·s/Btuth;

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For separation of number integers and decimals, use the symbol – point [.]





Units of measurement

namesymbol value in SI unit:
1 degree fahrenheit hour per BtuIT °F·h/BtuIT≈ 1.895 634(1), (2)
1 degree fahrenheit hour per Btuth °F·h/Btuth≈ 1.896 903(1), (3)
1 degree fahrenheit second per BtuIT °F·s/BtuIT≈ 5.265 651 × 10-4(1), (2)
1 degree fahrenheit second per Btuth °F·s/Btuth≈ 5.269 175 × 10-4(1), (3)


(1) - Btu - British thermal unit;

(2) - IT - common unit, international;

(3) - th - thermochemical unit;