00:01
Thermal conductivity, let us call it as tc.
00:11
Now this is the ability of a material or a given substance to conduct or transfer heat.
00:24
Now every substance has its own capacity to conduct heat.
00:29
The thermal conductivity, it is denoted by the simple kappa.
00:33
This is given by the formula ql divided by a into delta t.
00:42
So here k is the thermal conductivity.
00:46
Q is the heat transferred.
00:49
L is the distance between the two isothermal planes.
00:55
A is the area of the surface and delta t is the difference in temperature or change in temperature.
01:07
Now we don't know what kind of material is given or mentioned in the question.
01:14
So let us discuss about the effects of temperature, effects of temperature on thermal conductivity of both metals and nonmetals.
01:28
Now in the case of metals, the heat conductivity of metals is attributed to the presence of free electrons.
01:39
Presence of free electrons.
01:44
Now it is somewhat proportional to the product of the absolute temperature.
01:47
So this is given by a law which is weidman -france law.
01:54
Wideman -france law.
01:58
And according to this law, the given equation is that kappa divided by sigma, this is equals to temperature t.
02:08
So here kappa is the thermal conductivity and sigma is the electrical conductivity of the material and t is the temperature.
02:16
So here we can say that the thermal conductivity of a metal or a pure metal is shows a little variance with increase in temperature...