Lesson 3.3 - Electric Potential

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RECALL: GRAVITY

Remember the negative is due to the reference point chosen is infinity. It requires negative work to bring an object from infinity to the point r.

ELECTRICAL VS GRAVITY

Since the two force have the same mathematical form, we can use the same argument for the area under the curve determine the change in potential energy.

Again we chose infinity as our reference point and approach the point r.

The main difference here between Electrostatic potential and the gravitational potential is the sign.

LET'S GO BACK TO GRADE 9

We used a term electric potential difference when referring to the change in potential energy of a unit charge, across a portion of a circuit. It was also called voltage [measured in J/C].

We can now broaden this definition to any electric field, not just one confined to a conductor.

We have an equation of the electric potential energy of bringing a charge \(q_2\) from infinity to a distance r away from a charge \(q_1\).

VOLTAGE

If we define V to be the change in potential of a unit charge and consider \(q_2\) to be the unit charge.


This defines the Electrical potential difference. Note that this is a scalar.

EXAMPLE PROBLEM #1


SOLUTION:

EXAMPLE PROBLEM #2


SOLUTION:

EXAMPLE PROBLEM #3




SOLUTION:

EQUIPOTENTIAL LINES

We can generate lines that represent a surface where the potentials are the same. They are at right angles to the field lines.


最后修改: 2025年06月19日 星期四 16:35