# Phy: concept of potential

I don't really know what a potential is, it is very abstract...

1.From V=U/q ,potential=electric potnential energy per charge?? From V=Ed,

potential is about electric field ?

2.A positively charged metal rod is placed next to an earthed metal rod,Why the

earthed metal rod has 0 potential ??

3.What are the features of potential(i.e how can I identify if there is a potential...a

flow of current?? )

or any conditions for potential to exist?

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• 最佳解答

In brief, "electric potential" is analogous to "height" in mechanics (i.e. in a gravitational field).

1. V = U/q is the definition of potential, i.e. energy per unit charge.

As said above, the analogy in mechanics is : h = (mgh)/mg

where h is the height above ground, mgh is the (gravitational) potential energy, and mg is the weight of an object.

Because a potential difference gives rise to an electric field, the equation E = V/d relates the two physical parameters V and E.

2. It is a common practice to take the potential of the earth (or earth potential) as a reference, and gives it a vlaue of 0 volt. This is similar to the practice in mechanics that we usually takes the ground as referece of zero gravitational potential.

Any object that connects to the earth must acquire the potential as that of the earth, i.e. 0 volt. If not, charges would flow until the potential of the object becomes the same as that of the earth.

3. As said above, electric charges gives rise to a potential and hence an electric field.

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