Unformatted text preview: charge must be taken into account. Electric Potential Energy
Answer Next, draw a picture of the situation: q=+1nC rB rA
+qo List what quantities we know:
q!=!+1.0x10–9C Electric Potential Energy Example
A proton is placed 3.0cm to the right of a
+1.0nC charged sphere. It is then brought
in to a distance of 1.0cm from the sphere.
What is the change in potential energy of
the proton? Answer
Deﬁne a coordinate system.
Choose the sphere as r!=!0. Any outward
distance would be positive. Electric Potential Energy
Answer Start with: ∆Ue,A→B = ke q1 q2 1
rA ∆Ue = (8.99 × 109 Nm2 /C2 )(+1.6 × 10−19 C)(+1 × 10−9 C) ∆Ue = 9.60 × 10−17 J 1
0.01 m 0.03 m qo!=!+e!=!+1.602x10–19C
rA!=!0.03m This is a positive value so potential energy increased. rB!=!0.01m What if we substituted in an electron for the proton?...
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