Thermal Conductivity Definition

[Kasper_NYC]

Hi,

I have read that Thermal Conductivity means: “The thermal conductivity of a substance is the quantity of heat in cal/sec passing through a body 1 cm thick with a cross section of 1 sq. cm when the temperature difference between the hot and cold sides of the body is 1 deg. C.” http://www.lib.umich.edu/dentlib/Dental_tables/Thermcond.html

Does it means also how fast a substance can increase or decrease its temperature when is in contact with a heater or colder fount? For example, will it means that in the case of the Alumina (recrystallized), that its index is 38.7 (mcal/s) / (cm^ C/ cm), 1 cubic centimeter will absorbs 0.0387 cal /second, having 1 square cm of surface in contact with the heat fount?

I am interested into find the formula that let's to calculate how fast a given mass of substance warms up or colds down by second, in an ideal system (without losses of heat).

The other question is if “1 (cal/sec) / (cm2 C/cm) = 419 W/m K”; is 419 W/m K equivalent to 4.19 W/m K? (http://hyperphysics.phy-astr.gsu.edu/Hbase/tables/thrcn.html#c1)

Thanks a lot.

PS – I apologize for my English, I am learning it.

 

[Kasper_NYC]

Excuse me please,

The other question should be: " If 1 (cal/sec) / (cm2 C/cm) = 419 W/m K”; is it 419 W/m K equivalent to 4.19 W/cm K?"

Thanks again.

 

[astrokreng]

Hello,

Yes, thermal conductivity is a measure of how well a substance can conduct heat. In other words, it tells us how quickly heat can move through a material. So, in your example, a substance with a higher thermal conductivity (like alumina) will be able to absorb more heat per second than a substance with a lower thermal conductivity.

The formula for calculating the rate of temperature change in a substance is dependent on several factors, including the substance's specific heat capacity, its mass, and the amount of heat being applied. In an ideal system without heat losses, the change in temperature can be calculated using the formula Q = mcΔT, where Q is the heat energy, m is the mass, c is the specific heat capacity, and ΔT is the change in temperature.

As for your second question, yes, 1 (cal/sec) / (cm2 C/cm) is equal to 419 W/m K, which is equivalent to 4.19 W/m K. This is because watts (W) and calories per second (cal/sec) are both units of power, and they can be converted using the conversion factor of 1 W = 4.1868 cal/sec.

I hope this helps clarify the concept of thermal conductivity for you. Keep up the good work in learning English!