Positively charged rod to an uncharged electroscope

In summary, the conversation discusses the behavior of charges in an electroscope when a positively charged rod is brought near it. The question is whether negative charges are attracted to the knob or positive charges are repelled to the vanes. It is concluded that only the negative charges are free to move in the electroscope, while the positive charges are fixed in the metal atoms, leading to the latter explanation being correct.
  • #1
PhysKid24
22
0
Hi I was just wondering what the answer to the following question would be:

If you bring a positively charged rod to an uncharged electroscope causing the vanes or leaves inside to diverge, are negative charges attracted to the knob of the electroscope or do positive charges repel to the vanes of the electroscope? I think it's the latter, but not sure why it also couldn't be the first.
 
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  • #2
In the electroscope, which is a solid conductor, only the negative charges (electrons) are free to move. The positive charges (protons in the metal atoms) are fixed in a lattice structure (the metal atoms are not free to move).
 
  • #3


The correct answer is that positive charges repel to the vanes of the electroscope. This is because the positively charged rod will induce a separation of charges within the electroscope, with the positively charged rod attracting negative charges to the knob of the electroscope and repelling positive charges to the vanes. This creates a net positive charge on the vanes, causing them to diverge. The knob of the electroscope remains neutral in this scenario.
 

FAQ: Positively charged rod to an uncharged electroscope

What is a positively charged rod?

A positively charged rod is an object that has an excess of positive charge. This means that it has more protons than electrons, resulting in a net positive charge.

What is an uncharged electroscope?

An uncharged electroscope is a scientific instrument used to detect the presence of electric charges. It consists of a metal rod with two thin metal leaves hanging from the bottom. When an electric charge is applied to the metal rod, the leaves will either repel or attract each other, indicating the presence and polarity of the charge.

How does a positively charged rod affect an uncharged electroscope?

When a positively charged rod is brought near an uncharged electroscope, the positive charge on the rod will attract the electrons in the metal rod of the electroscope. This will cause the electrons to move away from the leaves, leaving them with a net positive charge. The leaves will then repel each other, indicating the presence of a positive charge.

What happens if a positively charged rod touches an uncharged electroscope?

If a positively charged rod touches an uncharged electroscope, the excess positive charge from the rod will transfer to the electroscope, causing the leaves to repel each other. This indicates that the electroscope is now positively charged.

Can an uncharged electroscope be used to detect the polarity of a positively charged rod?

Yes, an uncharged electroscope can be used to detect the polarity of a positively charged rod. When the rod is brought near the electroscope, the leaves will either repel or attract each other, indicating the polarity of the charge on the rod. If the leaves repel, the rod is positively charged. If the leaves attract, the rod is negatively charged.

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