Electrostatics: Charging a sphere by induction

In summary, the conversation discusses the phenomenon of charging a metallic sphere using induction and the flow of electrons from ground to sphere in certain cases. The explanation given is that the ground acts as an infinite source of charge and when a positively charged object is brought near the sphere, electrons from the ground are attracted to neutralize the positive induced charges on the sphere. It is suggested to post conceptual questions in general or classical physics forums for better responses.
  • #1
harini07
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2

Homework Statement



this is a theoretical question.please consider the situation as follows:
we are charging a metallic sphere using induction phenomenon with the help of a postively charged metallic rod and while on grounding the electrons flow from the ground to the sphere rather than sphere to ground, why?

Homework Equations



while charging by induction, the part of the material being induced near to the inducing material gets opposite charge of the inducing material and the other half which is away gets opposite polarity which is same as that of the inducing material's polarity.

The Attempt at a Solution


lets say when we bring a negatively charged plastic rod to an uncharged metallic sphere, the part nearer to the inducing material gets positive charge and the other half is negatively charged.on grounding the electrons flows from the sphere to the Earth and now the sphere as a whole becomes positively charged. but in the aforementioned case, why does the electron flows from ground to the sphere? what happens in the two cases? please explain.
 
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  • #2
Ground is an infinite source (supply) of charge. When the neutral sphere is grounded, ground either absorbs or supplies electrons depending on the incident field.

If you took a positively charged object near the sphere, it will attract electrons on the sphere and the charges will distribute on the sphere such that the net field inside the sphere is zero. Since the incident field is from +vely charged object, electrons will be attracted from the ground on the sphere. These attracted electrons will neutralize the positive induced charges and the sphere will now have only negative induced charges.

If you disconnected the sphere from the ground, the sphere will have a net negative charge.

So, if the incident field is from +ve charge, electrons will flow from ground to sphere and if the incident field is from -ve charge, electroms will flow from sphere to ground.
 
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  • #3
Thanks.It helped me :)
 
  • #4
Well, it looks like I'm going to get a warning soon for providing direct answers in the HH section..?:)
It would be better if you posted such conceptual questions in general physics or classical physics forums..
harini07 said:
Thanks.It helped me :)
You're welcome!
Some mentor or SA will come with an even better explanation (and a warning for me:-p)..
 
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  • #5
cnh1995 said:
Well, it looks like I'm going to get a warning soon for providing direct answers in the HH section..?:)
It would be better if you posted such conceptual questions in general physics or classical physics forums..

You're welcome!
Some mentor or SA will come with an even better explanation (and a warning for me:-p)..
oh is it? yup i will do it in the future. *posting conceptual questions in classic physics forum. instruction noted.* :)
 

Related to Electrostatics: Charging a sphere by induction

1. How does charging a sphere by induction work?

Charging a sphere by induction involves bringing a charged object near the sphere, causing a separation of charges within the sphere. This creates an electric field that induces a charge on the surface of the sphere.

2. Can any material be charged by induction?

Yes, any material that conducts electricity can be charged by induction. However, the amount of charge induced will depend on the material's ability to conduct electricity.

3. What is the difference between positive and negative charges in electrostatics?

Positive charges have a surplus of protons, while negative charges have an excess of electrons. In electrostatics, opposite charges attract each other, while like charges repel.

4. How does the distance between objects affect the amount of charge induced in electrostatics?

The amount of charge induced in electrostatics decreases as the distance between objects increases. This is because the strength of the electric field decreases with distance.

5. Is charging a sphere by induction a permanent process?

No, charging a sphere by induction is a temporary process. Once the charged object is removed, the induced charge on the sphere will dissipate and the sphere will return to its neutral state.

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