1. Textbook: 7.4 Homework: pg. 358 – 359 #1 – 8
Electric Potential
Textbook: 7.4
Homework: pg. 358 – 359 #1 – 8

3. Electric Potential Energy
Work done is the change in the electric
potential energy of the charge in an electric field.
The electric potential energy stored in a system with two charges q1 and q2, separated by a distance r is:
Ex. Calculate the electric potential energy stored in a hydrogen atom:
- q = 1.60 x C
- r = 5.29 x m
q1q2 < 0 charges are bound
q1q2 > 0 charges are unbound

4. Electric Potential
Electric potential energy per unit charge is referred to as electric potential or just potential.
The electric potential (V) a distance r away from a charge q is:
The change in electric potential between two points is the electric potential difference V (also know as the voltage)

5. Important Relationships
In general
For a parallel plate
(electric field,  = constant)
Pg #1 - 4

6. Draw two equal positive point charges and connect them with a line.
(a) Is there a point on the line at which the electric field is zero?
(b) Is there a point on the line at which the electric potential is zero?
(c) Explain the difference between the two answers.

7. A positive test charge of 1
A positive test charge of 1.5 x 10-6 C is placed in an electric field 10 cm from another charge of magnitude x 10-6 C that is anchored in place.
a) What is the electric potential energy of the test charge? [-6.8 x 10-1 J]
b) What is the potential difference between the test charge’s initial position and a point 5.0 cm closer to the negative charge? [-4.5 x 105 V]