We commonly experience electric potential in the form of a battery.
Electric potential and electric potential energy are two closely related concepts in the science of electricity and magnetism. At first glance, they seem almost identical, which makes it difficult to clearly understand the distinction between them. The textbook explanation is simply that electric potential is equal to electric potential energy per unit charge. For many people, however, this definition does little to promote a clear, intuitive understanding of the relationship between these two concepts.
Instructions
Terminoloy and Definitions
1. Use the name "voltage" whenever you think of electric potential. This helps to diminish confusion between the two concepts.
2. Focus on the "potential energy" part of "electric potential energy." This reminds you that it operates in much the same way as gravitational potential energy. It is easier to visualize and experience gravitational potential energy, because it is simply the energy an object has when it is located some distance above the ground.
3. Write down the formulas for both concepts, and notice the difference. Electric potential energy equals kQq/r and electric potential equals kQ/r. Electric potential, or voltage, only has one Q in the numerator, meaning that voltage does not depend on the size of the other charge.
Comparisons and Examples
4. Lift a heavy object in one hand and a light object in the other. It takes more effort, or energy, to lift the heavier object. This demonstrates why a heavy object has more gravitational potential energy than a light object at the same height. You can directly compare this activity to a situation involving electric potential energy instead of gravitational potential energy.
5. Imagine that you are moving two glass balls toward a big, positively charged metal plate. One has a strong positive charge and the other has a weak positive charge. It will be more difficult to move the ball with the strong charge, so this ball will gain more electric potential energy. The amount of potential energy depends on the strength of the charge you are moving.
6. Imagine that the charged balls are gone, and all you have now is the electrically charged metal plate. You cannot determine the electric potential energy, because you have no charged ball to move toward the plate.
7. Look again at the formula for voltage and note that the only variables are Q (the charge on the plate) and r (the distance from the plate). The voltage does not depend on the amount of charge on the other object. Voltage only tells you a situation's ability to give electric potential energy to a charged object.
8. Look at a AA battery. It will say "1.5 volts." This can remind you that electric potential, or voltage, does not depend on the size of another charge, because a battery is 1.5 volts no matter where you install it.
