The potential difference (V) between two points is the work done in moving a charge of one coulomb from one point to the other.
It is a scalar quantity with an SI unit of volt (V).
A potential difference of 1 volt exists between two points when 1 joule of energy is expended in moving 1 coulomb between them. 1 V 1 J C1
Potential difference is often referred to as voltage for convenience, as it is measured in volts.
POTENTIAL DIFFERENCE
V voltage,W work, Q charge V W
Q
When you move a positive charge towards another positive charge,work must be done to overcome the force of repulsion between the charges.This energy is stored (potential) energy.
£
Work W done in bringing a charge Q through a voltage V
≥ £ Concept of zero potential
When two charges are very far apart, there is no force between them. If they are moved about at this distance, no work is done. Charges at great distance (infinite distance) are said to be at zero potential. For practical purposes we take the Earth as our zero potential. The potential of the Earth (a very large spherical conductor) is not noticeably affected by charges moving towards or away from it.When a conductor is earthed, i.e. connected to earth by a conductor, it means that its potential is brought to zero.
Potential
The potential difference between a point and the earth is called the potential of that point.
Number of coloumbs transferred
≥ £
Word done in transferring 1 coloumb
≥ W QV B
16 A
Fig 16.1: Illustration of work being done on a charge to move it against an electric field causing an increase in its potential. An energy source does work in moving charge from A to B; the elec- tric field does work in moving charge back from B to A.
ALESSANDRO VOLTA, 1745–1827 (ITALIAN) He developed the first chemical cell and discovered the relationship between capacitance and electrical potential.The SI unit of potential difference is named in his honour.
