R7: What is the electric potential at A?
R8: Explain why the electrical potential at B is
the same as it is at A.
R9: Label points C: all the points along the ver-
tical line through the rightmost charge where the
electric potential has the same value as at A.
R10: Continuing with the same diagram, the
shape of the equipotential in the plane of the page
happens to be a circle. Using your answers to the
last few questions, sketch the equipotential that
passes through A.
-2q
D
X
A
q
X
B