What does the conductivity of a material depend on ?

This means that even if a material has a high energy gap, it can still have a high conductivity if it has a high free electron density. In summary, the conductivity of a material is primarily determined by its free electron density, not its energy gap.
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Not sure if this belongs in this subforum or not...if not my apologies

What does the conductivity of a material depend on: the energy/band gap of the material or the free electron density of the material?

We were posed this question on an exam and I said the answer was the energy gap of the material because we had discussed earlier how even if you pumped a large amount of free electrons into a piece of wood(thereby...at least as far as I can recon...increase its free electron density) it would not make it a better conductor(what I would think would mean to increase its conductivity) since it would still have a high energy gap.

Apparently this was the wrong answer and when I tried to make this argument to my professor he replied that in fact the energy gap was dependent upon the conductivity...

Is this right?

I have yet to find anything that says as much but have found things that state the opposite.
 
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  • #2
The conductivity of a material depends on its free electron density. The energy gap of the material only affects how much energy is needed to excite electrons to higher energy states and thus become free to contribute to conduction.
 

FAQ: What does the conductivity of a material depend on ?

1. What factors affect the conductivity of a material?

The conductivity of a material depends on several factors, including its physical properties such as its composition, structure, and temperature. It also depends on the presence of impurities or defects within the material.

2. How does the composition of a material affect its conductivity?

The composition of a material refers to the elements or compounds that make up the material. The conductivity of a material is affected by the number of free electrons available for conduction, which is determined by the composition of the material. For example, metals have a high conductivity due to their abundance of free electrons.

3. Does the structure of a material play a role in its conductivity?

Yes, the structure of a material can greatly impact its conductivity. In materials with a crystalline structure, such as metals, the atoms are arranged in a regular pattern, allowing for easy movement of electrons and high conductivity. In contrast, materials with an amorphous structure, such as glass, have a more disordered arrangement and lower conductivity.

4. How does temperature affect the conductivity of a material?

The conductivity of a material generally decreases as temperature increases. This is because higher temperatures cause the atoms to vibrate more, disrupting the movement of electrons and reducing conductivity. However, in some materials, such as semiconductors, conductivity may increase with temperature due to an increase in the number of free electrons.

5. Can impurities or defects affect the conductivity of a material?

Yes, the presence of impurities or defects within a material can significantly impact its conductivity. These impurities or defects can act as barriers to the movement of electrons, reducing conductivity. In some cases, intentional addition of impurities can be used to control the conductivity of a material, as seen in the doping of semiconductors.

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