Definition of Electric Potential - Examples

Definition of Electric Potential

































Suppose that a charge of 2 coulombs has 40 joules of electrical potential energy. What is the electric potential of that charge?

V = P.E./q = (40J)/(2C) = 20 (J/C) = 20V.

Twenty volts.


Write the units for electric field strength in terms of volts.

work = force times distance
J = Nm

Field strengh is measured in N/C.
N/C = (Nm)/(Cm) = J/(Cm) = (J/C)/m,
J/C = V,
so N/C = V/m = volts/meter.

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Unbalanced static electric charges can reach potentials of millions of volts. However, the amount of charge involved is always small. How much electrical potential energy is stored in an unbalanced charge of one micro-coulomb at a potential of one million volts?

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Suppose that a 1-meter diameter metal sphere is placed in a vacuum and charged up to a potential of 1 million volts relative to ground.

What is the electric potential of the vacuum at a point one centimeter outside of the sphere?

The potential measures the work per unit charge needed to approach the sphere, so the vacuum near the sphere is at a potential of nearly 1 million volts.

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A bird sitting on a high tension line has both feet at a potential of 100,000V. The bird is not hurt because the potential difference between its feet is zero. Thus, no charge can flow through the bird.

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