1. Seatwork:
1. Find the electric potential at (3.0m,3.0m) due to a point charge q =
-2.0 C located at (-3.0m,3.0m)
2. Find the electric potential at (-3.0m,-1.0m) due to three point
charges:
q1 = 2.0 C at (1.0m,0)
q2 = -1.0 C at (0,0)
q3 = -0.10 C at (-3.1m,-1.1m)
3. A charge q = 1.0 C is placed at the origin. Find the electric
potential at
a. (1.0m,0 m)
b. (0,1.0m)
c. (0,-1.0m)
d. (-1.0m,0)
e. What do you notice in your answers from 3a to 3d.

2. Seatwork:
4. From #3, draw a line connecting points with a potential of
a. V = 9.0 x 109 Volts
b. V = 5.0 x 109 Volts
c. V = 1.0 x 109 Volts
d. What can you conclude about the shape of the line?
5. A spherical balloon contains a positive charge at its center. As the
balloon is inflated to a greater volume, the electric potential on the
surface
a. increase
b. decrease
c. remains the same
6. Intuition Test. A positive charge is under the influence of an
electric potential. The charge will tend to
a. go to regions of lower potential
b. go to regions of higher potential
c. stay in its original position

3. Seatwork:
7. Two points A and B are located within a region in which there is an
electric field. The potential difference ΔV = VB - VA is
a. positive
b. negative
c. zero
8. A negative charge is placed
at A and moved to B. The
change in potential energy
of the charge-field system is
a. positive
b. negative
c. zero

4. Seatwork:
9. At a certain distance from a point charge, the magnitude of the
electric field is 500 V/m and the electric potential is 3.00kV.
a. What is the distance to the charge?
b. What is the magnitude of the charge?
10. Three charges are at the vertices of
an isosceles triangle. Calculate the
electric potential at the midpoint of
the base with q = 7.00 µC.
11. Show that the amount of work
required to assemble four identical
point charges of magnitude Q at the
corners of a square of side s is
5.41kQ2/s.

5. Seatwork:
→
12. A particle with a charge of +4.20 nC is in a uniform electric field E
directed to the left. It is released from rest and moves to the left; after is has
moved 6.00 cm, its kinetic energy is found to be +1.50 × 10− 6 J.
(a) What work was done by the electric force?
(b) What is the potential of the starting point with respect to the end point?
→
(c) What is the magnitude of E?
Recall the formula for the conservation of energy:
1
2
2
mvi + Ui = 1 mvf + Uf
2
2