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Physics Lesson 14.5.1 - The Meaning of Electric Potential
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Welcome to our Physics lesson on The Meaning of Electric Potential, this is the first lesson of our suite of physics lessons covering the topic of Electric Potential, you can find links to the other lessons within this tutorial and access additional physics learning resources below this lesson.
The Meaning of Electric Potential
In all quantities discussed so far in this section, a test charge denoted by Q0 was included in the formula, as it was necessary to determine and write the formulae. For example, the electric force F exerted by a charge Q on a test charge Q0 placed at distance r from it, is
Also, the electric field E produced by the charge Q at a distance r from a test charge Q0 requires the presence of this test charge, i.e.
= k Q/r2
despite the charge Q0 does not appear in the final version of the electric field formula.
Finally, the electric potential energy EPE involves the presence of the test charge Q0 as
What if we look for a new quantity that characterizes let's say the electric field E or the electric potential energy EPE produced by the charge Q at a distance r from it but which is independent from the test charge Q0? It would be very helpful as no external factors such as the test charge Q0 were needed anymore. This quantity would be an intrinsic property of the original charge alone.
Such a quantity exists and it is known as the electric potential, V. It is defined as the electric potential energy per unit charge.
For example, electric potential at the point A in the figure is VA.
Although the potential at the point A is independent from the test charge, we can place a test charge at this point to calculate the magnitude of electric potential.
Therefore, from definition of electric potential and based on the above figures, we obtain the following formula:
The formula of electric potential in terms of charge Q and distance r therefore is
= k × Q × Q0/r/Q0
Thus, we obtain for the electric potential V:
As you see, electric potential V is independent from the test charge Q0 as this does not appear in the final formula.
The unit of electric potential is Volt, V. From the formula derived from definition of electric potential, it is easy to conclude that
Example 1
What is the electric potential produced by a 12 μC point charge at a distance of 30 cm from it?
Solution 1
We have: Q = 12 μC = 1.2 × 10-5 C and r = 30 cm = 0.3 m. Thus,
= 9 × 109 × 1.2 × 10-5/0.3
= 36 × 104 V
= 360 000 V
You have reached the end of Physics lesson 14.5.1 The Meaning of Electric Potential. There are 8 lessons in this physics tutorial covering Electric Potential, you can access all the lessons from this tutorial below.
More Electric Potential Lessons and Learning Resources
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- Definition Feedback. Helps other - Leave a rating for this definition (see below)
- Electrostatics Physics tutorial: Electric Potential. Read the Electric Potential physics tutorial and build your physics knowledge of Electrostatics
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- Electrostatics Practice Questions: Electric Potential. Test and improve your knowledge of Electric Potential with example questins and answers
- Check your calculations for Electrostatics questions with our excellent Electrostatics calculators which contain full equations and calculations clearly displayed line by line. See the Electrostatics Calculators by iCalculator™ below.
- Continuing learning electrostatics - read our next physics tutorial: Electric Flux. Gauss Law
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