PHYSICS E and M(20points)

"Electrical potential" refers to the work done required to bring a unit positive charge from infinity (where the potential is defined as zero) to the point in question in a potential field.

"Electrical energy" refers to the work done required to bring a charge from infinity to the point in question under a potential field.

The difference lies in the fact that "electrical potential" refers to a "unit positive charge", whereas "electrical potential energy" refers to any quantity of charge.

Follwoing from the above definition, we would have,

electrical potential energy (in Joule) = charge in coulomb x electrical potential (in volt)

In general, because places at infinity is regarded as those far from the influence of any charges, the potential at infinity can be taken as zero. In practice, for convenience reason, the potential of the earth is sometimes taken as a reference potential and be assigned a value of zero volt.

For example, given the electrical potential at a certain point be +10 v, say, then the eelctrical potential energy possessed by a +ve charge of 2 coulomb = 2 x 10 J = 20 J

For a negative charge of -2 coulomb at the same point, its electrical potential energy is = ( -2) x (10) J = -20 J