This preview shows pages 1–7. Sign up to view the full content.
Coulomb's Law Tutorial
Learning Goal:
To understand how to calculate forces between charged particles, particularly the
dependence on the sign of the charges and the distance between them.
Coulomb's law describes the force that two charged particles exert on each other (by Newton's third law,
those two forces must be equal and opposite). The force
exerted
by
particle 2 (with charge
)
on
particle 1 (with charge
) is proportional to the charge of each particle and inversely proportional to
the square of the distance
between them:
,
where
and
is the unit vector pointing
from
particle 2
to
particle 1. The force vector
will be parallel or antiparallel to the direction of
, parallel if the product
and
antiparallel if
; the force is
attractive
if the charges are of opposite sign and
repulsive
if the
charges are of the same sign.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document Coulomb's Law Tutorial
Part A
Consider two
positively charged particles, one of charge
(particle 0) fixed at the origin, and another of charge
(particle 1) fixed on the
y
axis at
. What is the net force
on
particle 0
due to
particle 1?
Express your answer (a vector) using any or all of
,
,
,
,
,
, and
.
ANSWER:
=
Correct
Coulomb's Law Tutorial
Part A
Part B
Now add a third,
negatively charged, particle, whose charge is
(particle 2). Particle 2 fixed on the
y
axis at
position
. What is the new net force
on
particle 0,
from
particle 1 and particle 2?
Express your answer (a vector) using any or all of
,
,
,
,
,
,
,
, and
.
ANSWER:
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document Coulomb's Law Tutorial
Part A
Part C
Particle 0 experiences a repulsion
from
particle 1 and an attraction
toward
particle 2. For certain
values of
and
, the repulsion and attraction should balance each other, resulting in no net force.
For what ratio
is there no net force on particle 0?
Express your answer in terms of any or all of the following variables:
,
,
,
.
ANSWER:
=
Correct
Part D
Coulomb's Law Tutorial
Part C
Now add a fourth
charged particle, particle 3, with positive charge
, fixed in the
yz
plane at
. What is
the net force
on particle 0 due
solely
to this charge?
Hint D.1
Find the magnitude of force from particle 3
What is the magnitude of the force on particle 0 from particle 3, fixed at
?
Hint D.1.1
Hint not displayed
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
Part C
Hint D.1
Find the magnitude of force from particle 3
Express your answer using
,
,
,
.
ANSWER:
=
Correct
Hint D.2
Vector components
The force vector points from
to
. Because
is symmetrically located between the
y
axis and
the
z
axis, the angle between
, the unit vector pointing
from
particle 3
to
particle 0, and the
y

axis is
radians. You have already calculated the magnitude of the vector above. Now break
up the force vector into its
y
and
z
components.
Express your answer (a vector) using
This is the end of the preview. Sign up
to
access the rest of the document.
This note was uploaded on 04/18/2010 for the course PHYS ? taught by Professor Zhou during the Spring '10 term at Georgia State University, Atlanta.
 Spring '10
 ZHOU

Click to edit the document details