Why Don't Metals Get Charged by Friction?

In summary, metal objects such as nails can get charged by friction like insulators, but the charge spreads over the entire surface of the metal instead of staying in one place. This can lead to small surface charge density, but in some cases, such as with the van der Graaf generator, the charge can build up. This phenomenon can also be used to magnetize metal, as demonstrated by the compass-making method used by Boy Scouts.
  • #1
manjuvenamma
102
0
Why don't metal objects such as a nail get charged by friction like the famous comb, plastic rod or glass rod - all insulators?
 
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  • #2
electric discharge through gases

Can some one kindly explain or give a reference link that explains why it happens what it happens in electric discharges through gases like William Crookes expermient of 1870s and JJ Thomsons experiments with cathode rays? Covering also such important aspects such as what would have happened if we did not remove air/gas in the tube? Why electrons did not ionise the gas inside at low pressures etc? Thanks in advance. Basically, I want to know how our present knowledge of atomic structure explains the experiments and its results?
 
  • #3
manjuvenamma said:
Why don't metal objects such as a nail get charged by friction like the famous comb, plastic rod or glass rod - all insulators?
They do.

You can make a compass this way. Googling, I can't seem to find it, but I was a Boy Scout... (I'm curious, so I'll look more tomorrow)
 
  • #4
manjuvenamma said:
Why don't metal objects such as a nail get charged by friction like the famous comb, plastic rod or glass rod - all insulators?
On an insulator, like a comb, the transferred charged stays where it was placed.
In a metal, the charge spreads over the entire surface of the metal, so that the surface charge density is usually small.
There are cases where the charge transferred to a metal can build up.
This happens in the van der Graaf generator.
 
  • #5
russ_watters said:
They do.

You can make a compass this way.
No charge is transferred when a boy (or girl) scout magnetizes metal.
 

1. Why don't metals get charged by friction?

Metals have a high number of free electrons, which are able to move freely within the material. This means that when a metal is rubbed against another material, the electrons are able to transfer and balance out any differences in charge, resulting in no net charge on the metal.

2. Can metals ever get charged by friction?

Yes, it is possible for metals to get charged by friction under certain conditions. For example, if the metal is in a dry environment and rubbed against a material with a significantly different electronegativity, it may develop a small charge. However, this charge is usually short-lived and easily dissipated due to the high conductivity of metals.

3. How do non-metals get charged by friction, but not metals?

Non-metals, such as rubber or plastic, have a much lower number of free electrons compared to metals. This means that when they are rubbed against another material, the transfer of electrons is not as efficient and a net charge can build up on the surface of the material.

4. Are there any other factors that affect the charging of metals by friction?

Yes, the surface roughness and contact area between two materials can also affect the transfer of electrons and the resulting charge. A larger contact area and smoother surfaces can lead to a more efficient transfer of electrons and a lower chance of charge build-up on the metal.

5. Is there any practical application for the fact that metals do not get charged by friction?

Yes, this property of metals is often taken advantage of in industries such as electronics and manufacturing. For example, in the production of electronic components, metals are often used as grounding materials to dissipate any static charge and prevent damage to sensitive components.

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