Static Electricity: Why We Get Shocks on Carpet & Door Knobs

In summary, there is a discrepancy between the expected positive charge on the human body and the observed negative charge when rubbing feet on the carpet. The triboelectric series oversimplifies the direction of electron movement, and the ease of movement is determined by factors such as electronegativity. Additionally, the movement of electrons causes an electric shock when touching a door knob.
  • #1
Biker
416
52
Here is the rub. Most of the online sources and in a kind of statement in my book says that we gain a negative charge when we rub our feet on the carpet. So when we touch a door knob we get a electric shock because the electrons is transferred from us to the door knob

However, Shouldn't it be the opposite? In the triboelectric series, Human body is on the top of the list.. So it is supposed to have a positive charge not a negative one.

Here is the series if you want it : http://soft-matter.seas.harvard.edu/images/8/8e/Tribo.png
 
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  • #2
Biker said:
Here is the rub. Most of the online sources and in a kind of statement in my book says that we gain a negative charge when we rub our feet on the carpet. So when we touch a door knob we get a electric shock because the electrons is transferred from us to the door knob

However, Shouldn't it be the opposite? In the triboelectric series, Human body is on the top of the list.. So it is supposed to have a positive charge not a negative one.

Here is the series if you want it : http://soft-matter.seas.harvard.edu/images/8/8e/Tribo.png

The positive charge is the proton. The negative charge is the electron. The proton has more mass than the electron, so has a higher inertia (resistance to movement). So it is easier to move an electron (negatively charged) than a proton (positively charged).
 
  • #3
Kyx said:
The positive charge is the proton. The negative charge is the electron. The proton has more mass than the electron, so has a higher inertia (resistance to movement). So it is easier to move an electron (negatively charged) than a proton (positively charged).
I haven't said anything about moving a proton... I said that the electrons moves from us to the carpet not the opposite. So we will be left with a positive charge.
 
  • #4
Biker said:
I haven't said anything about moving a proton... I said that the electrons moves from us to the carpet not the opposite. So we will be left with a positive charge.

Insulating materials are more likely to lose or gain electrons, so the socks that you wear are gaining/losing the electrons. By taking your foot off the floor, you are causing the electrons to no longer be able to get back to the carpet, so you are 'spreading' the charge around your body. Then when you touch the door knob, the electrons 'jump'.
 
  • #5
Biker said:
However, Shouldn't it be the opposite? In the triboelectric series, Human body is on the top of the list.. So it is supposed to have a positive charge not a negative one.
Usually you're rubbing your shoes against the carpet, not your skin. (But interesting question.)
 
  • #6
Biker said:
So when we touch a door knob we get a electric shock because the electrons is transferred from us to the door knob
The direction doesn't really matter, but if you wear shoes or socks, see Doc Al.
In addition, this triboelectric series is an oversimplification, you often get different regions of different charge, even if you rub two identical materials against each other.

Kyx said:
The positive charge is the proton. The negative charge is the electron. The proton has more mass than the electron, so has a higher inertia (resistance to movement). So it is easier to move an electron (negatively charged) than a proton (positively charged).
It is clear that electrons move, but that doesn't answer the question in which direction the electrons move.
 
  • #7
Kyx said:
The positive charge is the proton. The negative charge is the electron. The proton has more mass than the electron, so has a higher inertia (resistance to movement). So it is easier to move an electron (negatively charged) than a proton (positively charged).
mfb said:
It is clear that electrons move, but that doesn't answer the question in which direction the electrons move.
Nor is it an accurate description of why it is easier to get the electrons to go between materials. The outer electrons are much more loosely bound to the material than the inner electrons and nucleus. Which direction the electrons go depend on things such as the electronegativity of the materials.
 

1. Why do we get shocks on carpet and door knobs?

Static electricity occurs when there is an imbalance of electric charges between two objects. When we walk on carpet, our shoes rub against the carpet, causing one object (our bodies) to build up a negative charge and the other object (the carpet) to build up a positive charge. When we touch a door knob, the electric charges are then transferred, resulting in a small shock.

2. Why do some people get shocked more than others?

The likelihood of getting shocked from static electricity depends on a combination of factors, such as the type of material of the object being touched, the amount of moisture in the air, and the type of shoes being worn. For example, rubber-soled shoes can prevent the buildup of static electricity, while leather-soled shoes can increase it.

3. Can static electricity be dangerous?

In most cases, static electricity is harmless and only causes a small shock. However, in certain situations, such as in environments with flammable gases, static electricity can potentially lead to fires or explosions. It is important to take precautions and avoid generating large amounts of static electricity in these settings.

4. How can I prevent getting shocked?

To prevent getting shocked, you can try to reduce the buildup of static electricity. This can be done by wearing natural fiber clothing, using a humidifier to add moisture to the air, and avoiding activities that can generate static electricity, such as shuffling your feet on carpet. You can also touch a metal object, such as a doorknob, with the back of your hand before touching it with your fingers to discharge any built-up static electricity.

5. Can static electricity be used for anything useful?

Yes, static electricity has many practical applications. For example, it is used in photocopiers and laser printers to attract toner to paper, in air filters to attract and trap dust particles, and in spray painting to ensure an even distribution of paint. Static electricity is also used in some industries, such as electronics and textiles, for processes such as cleaning and removing dust or lint.

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