Selenium conducts electricity better in the light than in the dark

In summary, Selenium is a direct gap semiconductor with a band gap of about 2eV, making it more conductive in the presence of light. This is why it is commonly used in photocells. In the dark, the conduction band is essentially unoccupied, but when light is incident on it, electrons get excited and allow for the conduction of electricity. If electricity is passed through selenium in the dark, it will behave like any other insulator, with most of the electricity not being conducted. It is important to understand basic concepts such as Ohm's Law and resistance in order to fully comprehend the properties of conductors and insulators.
  • #1
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I was reading an article about Selenium and I found that Selenium conducts electricity better in the light than in the dark. Why is that so.And is that why they are used in photocells?
 
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  • #2
Yes, the reason is the same. Selenium is a direct gap semiconductor with a band gap (if you are not familiar with any of these terms, make sure you look them up) of about 2eV, which is right in the middle of the range of visible light. In the dark, the conduction band is essentially unoccupied, but when light is incident on it, electrons get excited to the conduction band, providing the ability to conduct electricity.
 
  • #3
But what do you think will happen if I pass electricity through selenium in the dark? I guess that most of the electricity will not be conducted but what will happen to the rest?
 
  • #4
The same thing that happens with any insulator.

There are some very basic concepts you need to learn first. I suggest you start with Ohm's Law and understand the concept of resistance. Then you can try to understand what conductors and insulators are.
 

1. How does selenium conduct electricity better in the light than in the dark?

Selenium is a semiconductor material, meaning that it has properties of both a metal and an insulator. When exposed to light, selenium atoms release electrons, making it easier for electricity to flow through the material.

2. Is there a significant difference in the conductivity of selenium in light versus dark conditions?

Yes, there is a significant difference in the conductivity of selenium in light versus dark conditions. Studies have shown that the conductivity of selenium can increase by over 100 times when exposed to light.

3. How does the conductivity of selenium change with different light intensities?

The conductivity of selenium increases with higher light intensities. This is because more light means more electrons are being released from the selenium atoms, making it easier for electricity to flow through the material.

4. Can other materials conduct electricity better in the light than in the dark?

Yes, there are other materials that exhibit the same behavior as selenium, conducting electricity better in the light than in the dark. These include other semiconductor materials such as silicon and germanium.

5. What are some potential applications of this property of selenium?

The ability of selenium to conduct electricity better in the light than in the dark has a wide range of applications, including solar cells, photodiodes, and light sensors. It can also be used in photocopying and xerography processes.

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