Question

A given system has the equipotential surfaces shown in the figure .

Here is a link:
http://session.masteringphysics.com/problemAsset/1122530/1/Walker.20.39.jpg

A)What is the magnitude of the electric field?
E=___ V/m

B)What is the direction of the electric field?
θ=____ degrees from the +x axis

C)What is the shortest distance one can move to undergo a change in potential of 2.50 V?
d=____mm

Answer 1

The electric field (E) =ΔV/d, and the electric field isconstant because the equipotential surfaces are evenly spreadout.

Therefore, from the diagram, E=(10-0)/d
to calculate d, use pythagoras' theorem and find altitude asgiven:
BD²=AB²+AD²
BD=√(4+x²)
BD²=BC²+DC²
BD=√(16+20+x²-2x√20)
∴4+x²=36+x²-2x√20
x=32/2√20
=3.58m

∴E=10/3.58 =2.8N/C

The direction of the field is shown in the diagram(purplelines)