1. What would you do differently if you were told Q is negative?
Two equal positive charges Q are located at the base of an equilateral triangle with sides of length a. What is the potential at point P (see diagram)? P a
“No way you are going to give us a test problem this easy!” Q Q
Are you going to complain if we do?
What would you do differently if you were told Q is negative?

2. An electron is released from rest at point P
An electron is released from rest at point P. What path will the electron follow? What will its speed be when it passes closest to either charge Q? P - a Q Q

3. Don’t mix up your big V’s and little v’s!
An electron is released from rest at point P. What path will the electron follow? What will its speed be when it passes closest to either charge Q?
vi=0 -
initial a
a/2
a/2 Q - Q
final v
Don’t mix up your big V’s and little v’s!

4. An electron is released from rest at point P
An electron is released from rest at point P. What path will the electron follow? What will its speed be when it passes closest to either charge Q?
vi=0 -
initial a
a/2
a/2 Q - Q
final v

5. Three equal positive charges Q are located at the corners of an equilateral triangle with sides of length a. What is the potential energy of the charge located at point P (see diagram)? P Q
=Q1 a a
What would be different if you were asked for the potential energy of the system of three charges?
Q2= Q Q
=Q3
What would happen if the charges were held at rest in the above configuration, and then released?