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I recently read in a Khan Academy article that the rate of energy exchange through heat across a material of thickness ##d##, surface area ##A##, and thermal conductivity ##k## can be approximated by $$\dot{Q} = \frac{kA\Delta T}{d}$$ where ##\dot{Q}## is the heat rate and ##\Delta T## the temperature difference between the two sides of the material.

However, I am a bit confused by why the thermal conductivity of the media on either side of the material in question does not affect that heat rate across the "middle media," ##\dot{Q}##. Referring to the included image, what if the thermal conductivity of the media composing the body of ##T_1## was close to zero? Would the heat rate across the middle media not be affected? According to the equation for ##\dot{Q}## above, it is not.

Is ##\dot{Q}## solely a function of temperature difference, independent of the "sandwiching" media involved?

Khan Academy article I'm talking about:

https://www.khanacademy.org/science...-heat-transfer/a/what-is-thermal-conductivity

UPDATE: I think I understand what's going on. I believe that the heat rate across any media is, in fact, independent of the surrounding media's thermal conductivity with temperature difference between the surrounding media being the only external parameter of any importance. Please correct me if I am wrong.

However, I am a bit confused by why the thermal conductivity of the media on either side of the material in question does not affect that heat rate across the "middle media," ##\dot{Q}##. Referring to the included image, what if the thermal conductivity of the media composing the body of ##T_1## was close to zero? Would the heat rate across the middle media not be affected? According to the equation for ##\dot{Q}## above, it is not.

Is ##\dot{Q}## solely a function of temperature difference, independent of the "sandwiching" media involved?

Khan Academy article I'm talking about:

https://www.khanacademy.org/science...-heat-transfer/a/what-is-thermal-conductivity

UPDATE: I think I understand what's going on. I believe that the heat rate across any media is, in fact, independent of the surrounding media's thermal conductivity with temperature difference between the surrounding media being the only external parameter of any importance. Please correct me if I am wrong.

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