What is potential and potential difference?

Answer 1

You can compare 'potential' with the height of an object, and 'potential difference' with the difference in height between two objects.

Height is not absolute, we always specify height with respect to some point of reference, such as 'sea level'. Objects above sea level we can designate as, for example, plus 1000 metres; objects below sea level we can designate as, for example, minus 500 metres.

The difference in height between these to objects will be +1000 - (-500) = 1500 metres.

In much the same way, potential depends upon from where it is measured. In many cases, we measure potential with respect to earth, although we could use any other reference point, in which case its potential would be different. For example one object may have a potential of +1000 V with respect to earth, while another has a potential of -500 V with respect to earth.

The potential difference between these two objects will be +1000 - (-500) = 1500 V.

To summarise, potential exists at a single point, and is always measured with respect to another point, such as earth. Potential is always assigned a polarity with respect to its point of reference. Potential difference is the difference in the potentials at two different points, and does not have polarity assigned to it (do not confuse 'sense' -the direction in which it acts- with 'polarity').

Finally, 'voltage' is another name for potential difference, not potential. It would be incorrect to ask "What is the voltage at this point with respect to earth".

Answer 2

A ball at the top of a hill has potential energy. As it rolls down the hill it is losing potential energy but it has kinetic energy.

Answer 3

Energy possessed by a group of point charges due to their positions is an example of electric potential energy of the charge system.

Answer 4

You need a voltage source, or a current through a resistance.

Answer 5

That is called a voltage.

Answer 6

voltmeter

Answer 7

e.g.battery