# Earthing a conductor?

1. Jul 9, 2014

### Hardik Batra

I have two sphere.

1) one with free electron, if i connected sphere with the earth by conducting wire all the free electron will flow to the earth.

2) one with positive charge, if i connected sphere with the earth by conducting wire then the electron from the earth will flow to the sphere and neutralize the positive charge

Why does this happen ? what this the reason behind this?

2. Jul 9, 2014

### UltrafastPED

The voltage difference is equivalent to a force ... which moves the excess charge from one reservoir to the other.

3. Jul 9, 2014

### sophiecentaur

Not 'all' the surplus electrons will flow to the Earth. The flow will stop when the charge is shared appropriately between Earth and the conductor.
The same thing will apply to the positively charged conductor.
In both cases there will be a net imbalance of + and - charges unless the two spheres have equal and opposite charges.

4. Jul 10, 2014

### Hardik Batra

In first condition,
the first sphere has excess of electron that will flow to the ground.

but happens in the second case.

Why the electron will flow from earth to the sphere.

5. Jul 10, 2014

### Drakkith

Staff Emeritus
Because a potential difference (voltage) exists between the sphere and the Earth. The electrons in the ground are attracted to the positive charge of the sphere and move towards it until the voltage between the ground and the sphere is zero.

6. Jul 10, 2014

### Hardik Batra

Earth has infinite number of free electron.
And it has greater attraction force on positively charge sphere.
then why the positive charge will not go from sphere to earth.?

7. Jul 10, 2014

### CWatters

Have a think about where the +ve charges are in an atom.

8. Jul 10, 2014

### UltrafastPED

Because most positive charges are not mobile. It is always much easier to move electrons.

9. Jul 10, 2014

### sophiecentaur

But moving electrons Away from an object is totally the equivalent of adding Positive charge.

10. Jul 10, 2014

### Drakkith

Staff Emeritus
The positive charges are the protons inside the nucleus of the atoms. These are generally immobile and cannot move, unlike the electrons which exist in the electron cloud around the nucleus and can be made to move fairly easily.

11. Jul 10, 2014

### ModusPwnd

I like the way sophiecentaur puts it. Positive charge does move, positively charged particles do not.

Last edited: Jul 10, 2014