This preview shows pages 1–2. Sign up to view the full content.
Physics 7B
WS E1 (rev. 3.0)
Page 1
E1. Coulomb’s Law
Questions for discussion
1
. Coulomb’s Law for the electrostatic force between two point charges is
F
=
qQ
4
"#
0
r
2
. (
ε
0
is
constant, equal to 8.85
×
10
12
C
2
/N
⋅
m
2
, which determines the relative strength of the electric force.
Some texts use the constant k
C
= 1/4
πε
0
, called Coulomb’s constant instead, which makes Coulomb’s
Law look even more like Newton’s law of gravitation!) This looks a lot like Newton’s law for the
gravitatational force between two point masses:
F
=
G mM r
2
. And indeed, because both forces are
“1/r
2
forces,” there are some mathematical similarities between them.
However, all similarities aside, can you think of any important
differences
between electrostatic
forces and gravitational forces?
2
. Two point charges q
1
= +2 C and q
2
= 3 C are fixed in place along the xaxis, as shown.
You have in your hand another point charge q, and you want to place it somewhere on the xaxis.
But you want to place it at a point where it will
stay
. That is, you want to place it at a point where
it will feel
no force
due to the fixed charges q
1
and q
2
. (Hint: Think about what the force looks like
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
This is the end of the preview. Sign up
to
access the rest of the document.
 Fall '10
 yildiz
 Physics, Charge, Force

Click to edit the document details