# Earth neutralises the charge?

1. Aug 8, 2015

### Brajesh kedia

When conductor is connected to earth..all the charges are shown to be flown to earth in textbook hc verma...But i found in its examples the charges are however not zero on conductor when it is connected to earth..
If it charge is not zero on connecting to earth how will the capacitor work...?

2. Aug 8, 2015

Where?

3. Aug 8, 2015

### sophiecentaur

If a charged plate is brought up to an Earthed (therefore uncharged) plate, charges will flow into and out of the plate (likes being repelled and unlikes being attracted), causing the plate to have a surplus of unlike charges. Remove the Earth connection and tat plate will have acquired a charge by Induction. Perhaps this is what the OP refers to?

4. Aug 8, 2015

### Staff: Mentor

Ah right, problably.

Things connected to earth have a potential difference of 0 V relative to ground, no matter how much charge density this requires in the current setup.

5. Aug 8, 2015

### sophiecentaur

The system reaches a minimum energy state - would be one way of putting it.

6. Aug 16, 2015

### Brajesh kedia

Anyone please give me a good explaination whats actually happening as maximum teachers say charges are zero on connecting otherwise capacitor wont work nd when doing sums they are saying that theory is not applicable here..

7. Aug 16, 2015

### sophiecentaur

I am not sure what you are getting at here. The charges (or any other variable) can be whatever the system starts with.
The right theory is always applicable. There can be zero net charge on a conductor but the charges can still be spread unevenly around it (polarisation) in the presence of an external field or nearby charged object.

8. Aug 16, 2015

### CWatters

Is this an example in your text book? Can you scan that example and post it here?

9. Aug 17, 2015

### Brajesh kedia

q` is bq/c whereas showing u another snapshot of hc verma where charges are flown to earth as a whole

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10. Aug 17, 2015

### Brajesh kedia

Charges have flown to earth as a whole when earthed in this case..!!

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11. Aug 17, 2015

### sophiecentaur

What people seem to be forgetting is that the charges on a conductor (eg Earth) can flow very easily. Excess charges will flow from a charged conductor to Earth until the PD is zero but that doesn't mean that there is no net charge on that conductor. If there is a local Field due to a nearby charged object, it is very easy for electrons to be attracted to or repelled from the local part of Earth. Do not confuse PD with Charge.
Search for "electrophorus" and you will see exactly how you can actually charge up a metal plate by connecting it to earth.