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E
ð
lisfræ
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i 2, vor 2007
28. Sources of Magnetic Field
Assignment is due at 2:00am on Wednesday, March 7, 2007
Credit for problems submitted late will decrease to 0% after the deadline has passed.
The wrong answer penalty is 2% per part. Multiple choice questions are penalized as described in the online help.
The unopened hint bonus is 2% per part.
You are allowed 4 attempts per answer.
B-Field from Moving Charges
Magnetic Field near a Moving Charge
A particle with positive charge
is moving with speed
along the
z
axis toward positive
. At the time of this problem it is located at the origin,
. Your task is to find the magnetic field
at various locations in the three-dimensional space around the moving charge.
Part A
Which of the following expressions gives the magnetic field at the point
due to the moving charge?
A.
B.
C.
D.
ANSWER:
Answer not displayed
Part B
Find the magnetic field at the point
.
Part B.1
Find the magnetic field direction
Part not displayed
Express your answer in terms of
,
,
, and
, and use
,
, and
for the three unit vectors.
ANSWER:
=
Answer not displayed
Part C
Find the magnetic field at the point
.
Express your answer in terms of
,
,
,
, and
, and use
,
, and
for the three unit vectors.
ANSWER:
=
Answer not displayed
Part D
Find the magnetic field at the point
.
Part D.1
Evaluate the cross product
Part not displayed
Part D.2
Find the distance from the charge
Part not displayed
Express your answer in terms of
,
,
,
,
, and
, and use
,
, and
for the three unit vectors.
[
Pr

04/19/2007 02:22 PM
MasteringPhysics: Assignment Print View
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http://session.masteringphysics.com/myct/assignmentPrint?assignmentID=1064958
ANSWER:
=
Answer not displayed
Part E
The field found in this problem for a moving charge is the same as the field from a current element of length
carrying current
provided that the quantity
is replaced by which quantity?
Hint E.1
Making a correlation
Hint not displayed
ANSWER:
Answer not displayed
Force between Moving Charges
Two point charges, with charges
and
, are each moving with speed
toward the origin. At the instant shown
is at position (0,
) and
is at (
, 0). (Note that the signs of the charges are not given because they are not needed to determine the magnitude of the forces
between the charges.)
Part A
What is the magnitude of the electric force between the two charges?
Hint A.1
Which law to use
Apply Coulomb's law:
where
is the distance between the two charges.
Part A.2
Find the value of
What is the value of
for the given situation?
Express your answer in terms of

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