Contents
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08_E4_ws4 - 1
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Name
Date
Pd
E&M Unit 4 - Magnetism: Worksheet 3
1. A straight wire 50 cm long conducts a 6.0 A current directed up out of the page. If the wire
experiences a force of 0.24 N to the right due to a magnetic field perpendicular to its length,
what is the magnitude and direction of the magnetic field?
2. A horizontal magnetic field of 2.0 x 10-3 T forms a 30˚ angle with a 0.75 m length of wire
carrying a 15.0 A current. What is the force acting on the wire?
3. A proton from a particle accelerator enters a uniform magnetic field of 0.080 T oriented
perpendicular to its path and follows a circular path with radius of 2.0 m. What is its
velocity? Sketch a diagram.
4. Below are two current carrying wires. Wire A has a current of 10.0 A downward and wire B
has a current of 5.0 A upward. (µo=1.26x10-6 )
2.0 m
1.0 cm
I2
a. What is the magnitude and direction of the magnetic field Wire B is in due
to A? Draw in the magnetic field on the diagram.
I1
A
B b. What is the magnitude and direction of the force on wire B due to this
magnetic field?
c. What is the magnitude and direction of the force on wire A?
©Modeling Workshop Project 2005
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E4 Magnetism ws 3 v3.2
5. Below are two current carrying wires. Both are carrying current into the paper. Draw a
vector indicating the direction of the magnetic field at the 3 points below the wires.
6. A titanium alloy disc (0.010 kg) and rails are shown viewed from the top. A magnetic field
of 2.0 T is coming out of the page. The distance between the rails is L = 0.02 meters. A
current of 120 amps runs through the disc.
a. What is the force on the disc?
b. How long must the track be to obtain a final velocity of 20 m/s?
Part 2 - Magnetic and Electric Forces Acting on a Moving Charge
An electron moves through a hole in a plate into a region with electric and magnetic fields.
The two fields and the particle's velocity are mutually perpendicular.
B into paper
Draw arrows in the diagram to
indicate the direction of the
electric and magnetic forces
acting on the particle.
x
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E
©Modeling Workshop Project 2005
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E
E4 Magnetism ws 3 v3.2
1. Ignoring the effects of gravity on the particle, state the conditions under which the particle
would continue to move in a straight line.
Write the equation that states the relationship between the electric and magnetic forces.
2. Suppose that the electric and magnetic fields are the same, but now the particle entering the
slit is moving twice as fast as before. Explain what effect this would have on the forces
acting on the particle. Sketch a force diagram for the particle, then draw a sketch of the path
the particle would now take.
3. Suppose that the electric and magnetic fields are the same, but now the particle entering the
slit is moving half as fast as before. Explain what effect this would have on the forces
acting on the particle. Sketch a force diagram for the particle, then draw a sketch of the path
the particle would now take.
4. A proton is accelerated through a potential difference of 2.5 kV. It enters a region between
two parallel plates separated by a distance of 0.10 m and have a potential difference of 250
V. Find the magnitude and the direction of the magnetic field (oriented perpendicular to E)
needed for the proton to pass undeflected between the plates.
©Modeling Workshop Project 2005
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E4 Magnetism ws 3 v3.2
Name
Date
Pd
E&M Unit 4 - Magnetism: Worksheet 4
Magnetic flux and induced ∆V
x
The following diagrams show a loop connected to a resistor and a bar magnet. In each situation,
determine the direction of the induced current in the loop and which side of the resistor has a
higher potential.
1.A magnet moves nearer a loop perpendicular to 2.A magnet moves away from a loop
the plane of the paper
perpendicular to the plane of the paper.
3. A magnet remains in place while the top of the 4. A magnet is brought near a loop in the
loop is pulled upward, bringing the sides of the
plane of the paper.
loop together.
5. A magnet remains in place while the loop,
originally perpendicular to the plane of the paper
is rotated CW into the plane of the paper.
©Modeling Workshop Project 2005
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6. A magnet remains in place while the
loop, originally in the plane of the paper is
rotated CW out of the plane of the paper.
E4 Magnetism ws 4 v3.2
Graphs of the magnetic flux through a loop as a function of time are shown below. For each
situation, sketch qualitative graphs of induced potential as a function of time.
©Modeling Workshop Project 2005
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E4 Magnetism ws 4 v3.2
Name
Date
Pd
E&M Unit 4 - Magnetism: Worksheet 5
When answering the questions, it is assumed this paper is lying on your desk. Down is toward the bottom of this paper, up is
towards the top, in is toward the floor, and out is toward the ceiling.
1. What direction will the electron below be forced?
3. The proton below is traveling out of the paper.
What direction will it be forced?
2. What is the charge on the particle below ?
4. The solenoid below has an iron bar to form an electromagnet.
Label the N and S poles of the electromagnet. Draw arrows
indicating the magnetic field before the iron bar, inside the iron
bar and after the iron bar
5. You want the proton below to pass through the plates undeflected. What is the direction of the magnetic field between the
plates? Draw it in.
6. The iron bar below is being forced to the right at through a magnetic field out of the paper. Sketch in an appropriate charge
distribution on the bar.
7. The loops below are being forced through a magnetic field out of the paper at a constant speed. Determine the direction of the
current in each loop.
8. Do the loops below have a clockwise current, a counterclockwise current or no current?
a) field strength is decreasing
b) field strength is increasing
c) field strength is constant
9. The questions below refer to the setup below.
A
a) Just before the switch is closed, what is the direction of the current through the ammeter? Explain.
b) Immediately after the switch is closed, what is the direction of the current through the ammeter? Explain.
c) A long time after the switch is closed, what is the direction of the current through the ammeter? Explain.
d) Immediately after the switch is reopened, what is the direction of the current through the ammeter? Explain.
10. On the loop below, the left side is the side closest to you.
a) If the magnet is forced toward the loop, what is the direction of the current in the loop?
S
b) What is the direction of the force on the loop? Explain
N
11. On the diagrams below, draw in arrows indicating the direction of the induced current in the coils. On one of the two explain
your reasoning. The arrows on the magnet indicate the direction the magnet is moving.
S
N
A
N
S
A
12. The wire to the right is carrying a constant current upward.
a) If the loop is pulled to the right, what direction is the induced current in the loop?
b)
b) Same question for a loop pulled straight up.
a)
I
c) Now the loop is stationary and the current in the wire is decreasing. What direction is the
induced current in the loop?
d) What direction is the net force on the loop as the current decreases? Explain.
13. To the right is a coil in a constant magnetic field pointing in to the paper.
Describe 4 different means of producing current from A to B in the resistor.
A
B