A positively charged elctroscope near a finger

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In summary, a positively charged electroscope will experience a slight decrease in deflection when approached by a finger due to polarization and partial neutralization of charges. If a neutral conducting metal rod is used instead of a finger, the effect would be more noticeable.
  • #1
Jimenen
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Homework Statement


A positively charged electroscope (with deflected leaves, obviously) is approached by your finger (but not touched). Will the deflection increase, decrease, or remain the same?


Homework Equations


None, purely conceptual


The Attempt at a Solution


I think the effect would be very slight. The electroscope would polarize the mlcls in your finger, causing a net attraction. The neg. charges in your finger near the electroscope woud repel some electrons down into the leaves and partially neutralize the positive charges in the leaves. This will cause the deflection to decrease slightly.

What my question really amounts to is:
Does a dipole induced by a conductor, in turn, polarize the conductor even a little.

Out of curiosity if the finger were replaced by a neutral conducting metal rod what would happen? I know the body is conductive, I'm just not exactly sure if the effect is the exact same in this case.

Thanks!
 
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  • #2
Well really, you'd need to put your finger bang in the middle to see any effect at all, hmmm, i doubt it would amount to much really, and you're right, if anything the deflection would decrease, and the conductor would be very very partially polarized.

And i think you're right, the effect would be a lot more obvious with a neutral conducting metal rod, an interesting question though! I'm sure someone has seen it before :P
 
  • #3




I would like to provide a response to the question with a more specific and detailed explanation.

Firstly, when a positively charged electroscope is approached by a finger, the deflection of the leaves would indeed decrease, but the extent of the decrease would depend on the distance between the finger and the electroscope. This is because the finger, being a conductor, would experience a force from the positively charged electroscope due to the attraction between opposite charges. This force would cause the electrons in the finger to redistribute, creating a dipole moment.

The dipole moment in the finger would then induce a dipole moment in the electroscope, causing the positive charges in the leaves to be partially neutralized by the induced negative charges. This would result in a decrease in the deflection of the leaves. However, the effect would be very slight as the distance between the finger and the electroscope would determine the strength of the induced dipole moment.

If the finger were replaced by a neutral conducting metal rod, the effect would be the same as the finger. This is because the body, whether it is a finger or a metal rod, is still a conductor and would experience the same force and redistribution of electrons.

In summary, the deflection of the leaves of a positively charged electroscope would decrease when approached by a finger or a neutral conducting metal rod due to the induced dipole moment in the conductor. The extent of the decrease would depend on the distance between the conductor and the electroscope.
 

1. How does a positively charged electroscope near a finger work?

A positively charged electroscope near a finger works by detecting the presence of positively charged particles in the finger. When a positively charged object, such as a finger, comes close to the electroscope, the positively charged particles in the object will repel the positively charged particles in the electroscope, causing the leaves of the electroscope to separate. This separation indicates the presence of a positive charge.

2. What is the purpose of a positively charged electroscope near a finger?

The purpose of a positively charged electroscope near a finger is to demonstrate the presence of a positive charge. This can be useful in experiments or demonstrations related to electricity and charge.

3. Can a positively charged electroscope near a finger detect any other types of charges?

No, a positively charged electroscope near a finger can only detect the presence of positively charged particles. It is not able to detect negative charges or any other types of charges.

4. How close does a finger need to be to a positively charged electroscope for it to detect the charge?

The distance at which a finger needs to be from a positively charged electroscope in order for it to detect the charge will vary depending on the strength of the charge. In general, the closer the finger is to the electroscope, the stronger the charge will appear to be.

5. Can a positively charged electroscope near a finger be used to measure the amount of charge?

No, a positively charged electroscope near a finger is not a precise instrument and cannot be used to measure the amount of charge. It can only indicate the presence or absence of a positive charge.

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