Conversion from Farenheit to degree celsius?

Question

The equation for thermal conductivity has a term (change in temperature). If this thermal conductivity is expressed in farenheit, how do I change it to degree celsius?
If it is from kelvin to degree celsius or vice versa, it is the same for both since this is a temperature difference.
However, why is this not the same for farenheit to degree celsius or vice versa?

Can anyone help me this? Thanks a lot.

For the thermal conductivity equation, to convert from farenheit to degree celsius is to multiply by 1.8 only. Why is this so?

Answer 1

I think you are confused by the difference between absolute temperature (as expressed on the Kelvin and Rankine scales) and our everyday temperature scales, Fahrenheit and Celsius, which incorporate arbitrary additive offsets.

The temperature *difference* is what is needed for the usual simple models of thermal conductivity. Temperature differences in Celsius and Kelvin are equal and are both measured in the Celsius degree; temperature differences in Fahrenheit and Rankine are equal and are measured in the Fahrenheit degree.

When you convert between the two different-sized degrees, you need to include a scale factor: the Kelvin~Celsius degree is larger, 1.8x the Rankine~Fahrenheit degree. (that is, a given difference in physical temperature might be expressed as T in Celsius degrees and 1.8 T in Fahrenheit degrees.)

So, the rules work like this:
to convert specific single temperatures in Celsius and Fahrenheit, you always need to deal with an additive constant and a scale factor.

To convert between the absolute temperature scales, Kelvin and Rankine, you only need to multiply or divide by 1.8.

To convert temperature differences measured in Celsius~Kelvin and measured in Fahrenheit~Rankine, you only need to multiply or divide by the scale factor 1.8.

To convert between either of the absolute scales (Kelvin ~ Rankine) and either of the offset scales (Celsius ~ Fahrenheit) you always need to include an additive constant. In addition, if you are converting between a scale based on the Celsius degree and one based on the Fahrenheit degree, you need to multiply or divide by the scale factor too.

Conductivity and heat storage depend on changes in temperature, not (in the useful, linearized models) on absolute temperature. So, "per °C" or "per K" in a specific heat or conductivity means the same thing. To convert from a "per °F" quantity to a "per K" quantity, multiply by 1.8. But if you are using a more complicated model that accounts for the variation in a property as a function of temperature, then you have to include the correct offset and things are not so simple.

Answer 2

To change from Fahrenheit to Celsius, you subtract 32 from Fahrenheit temperature and multiply by 5/9.
eg. 80 degrees Fahrenheit - 32 x 5/9 = 26.7 Celsius
Degrees Kelvin and degrees Celsius are the same except a different starting point, but Fahrenheit degrees are a different scale, being only 5/9 ths a Celsius degree.

Answer 3

To convert Fahrenheit temperatures into Celsius:

1) Begin by subtracting 32 from the Fahrenheit number.
2) Divide the answer by 9.
3) Then multiply that answer by 5.

Answer 4

A useful approximation for converting degree Celsius to Fahrenheit is to double and add thirty. To convert from Fahrenheit to degree Celsius, subtract thirty and halve. Between 0 and 40 degrees C this is accurate to about 5 degrees F, or roughly 2.5 C.

Answer 5

1 Farenheit degree =1.8 Cesius degree

Answer 6

huh