Download 14. An electron moving north encounters a uniform magnetic field. If

A1 Conceptual Physics
Spring 2013
Conceptual Physics Chapter Magnetism Outline
Hewitt: Chapter 36 & 37
Exercises: 17 Magnetism and Electromagnetic Induction
Magnetism
Chapters 36 & 37
Fill in the Charts completely
Variables introduced or used in chapter:
Quantity
Symbol
Units
Force
Charge
Speed
Magnetic Field
Area
Flux
Potential Difference
Formula Chart*
*In Class, we will use x for horizontal motion, and y for vertical motion instead of ‘d’
Magnetic Force
Flux
Potential Difference
Transformer
Define the following terms using COMPLETE SENTENCES:
Magnetism
Magnetic Poles
Magnetic Field
Magnetic Domain
Electromagnet
Galvanometer
Magnetism p 1
A1 Conceptual Physics
Spring 2013
Magnetism
Chapters 36 & 37
Voltmeter
Ammeter
Electromagnetic Induction
Faraday’s Law
Generator
Motor
Transformer
Step-Up Transformer
Electromagnetic Fields
Formulas:
F = qvB
F = BIL
Conventions:
Into Page X
Out of page
North – top of page
South – bottom of page
East – right side of page
West – left side of page
RHR: Fingers: B
Thumb: v or I (Direction particle is traveling)
Palm: F
Magnetism p 2
A1 Conceptual Physics
Spring 2013
Magnetism
Chapters 36 & 37
Magnetism Homework
1. A proton, with a charge of 1.6 x 10-19 C, moving east experiences a force of 8.8 x 10-19
N upward due to the Earth’s magnetic field. At this location, the field has a magnitude of
5.5 x 10-5 T to the north. Find the speed of the particle. [1.0 x 105 m/s]
2. A proton, with a charge of 1.6 x 10-19 C, moves perpendicularly to a magnetic field
that has a magnitude of 4.20 x 10-2 T. What is the speed of the particle if the magnitude
of the magnetic force on it is 2.40 x 10-14 N? [3.571 x 106m/s]
3. A proton, with a charge of 1.6 x 10-19 C, traveling to the right along the x-axis
(east) enters a region where there is a magnetic field of magnitude 2.5 T directed
upward along the y-axis (north). If the proton experiences a force of 3.2 x 10-12 N,
find the speed of the proton. [8.0 x 106m/s]
4. If an electron, with a charge of 1.6 x 10-19 C, in an electron beam experiences a
downward force of 2.0 x 10-14 N while traveling in a magnetic field of 8.3 x 10-2 T west,
what is the direction and magnitude of the velocity? [1.51 x 106m/s, north]
5. A uniform 1.5 T magnetic field points north. If an electron, with a charge of 1.6 x 10-19
C, moves vertically downward (toward the ground) with a speed of 2.5 x 107 m/s
through this field, what force (magnitude and direction) will act on it? [6.0 x 10-12 N,
west]
6. A proton, with a charge of 1.6 x 10-19 C, moves straight upward (away from the
ground) through a uniform magnetic field that points from east to west and has a
magnitude of 2.5 T. If the proton moves with a speed of 1.5 x 107 m/s through this field,
what force (magnitude and direction) will act on it? [6.0 x 10-12 N, south]
7. An alpha particle (the nucleus of a helium atom, carrying a charge of 3.2 x 10-19
C) moves at 5.5 x 107 m/s at a right angle to a magnetic field. If the particle
experiences a force of 1.5 x 10-14 N due to the magnetic field, when what is the
magnitude of the magnetic field? [8.52 x 10-4 T]
8. A wire 36 m long carries a current of 22 A from east to west. If the maximum
magnetic force on the wire at this point is downward (toward Earth) and has a
magnitude of 4.0 x 10-2 N, find the magnitude and direction of the magnetic field at this
location. [5.05 x 10-5 T, south to north]
9. A 6.0 m wire carries a current of 7.0 A toward the east. A magnetic force of 7.0 x 10-6
N acts on the wire upwards. Find the magnitude and direction of the magnetic field
producing the force. [1.67 x 10-7 T, north]
10. A wire 1.0 m long experiences a magnetic force of 0.50 N due to a perpendicular
uniform magnetic field. If the wire carries a current of 10.0 A, what is the magnitude of
the magnetic field? [0.050 T]
Magnetism p 3
A1 Conceptual Physics
Spring 2013
Magnetism
Chapters 36 & 37
11. The magnetic force on a straight 0.15 m segment of wire carrying a current of 4.5 A
is 1.0 N. What is the magnitude of the component of the magnetic field that is
perpendicular to the wire? [1.48 T]
12. The magnetic force acting on a wire that is perpendicular to a 1.5 T uniform
magnetic field is 4.4 N. If the current in the wire is 5.0 A, what is the length of the wire
that is inside the magnetic field? [0.59 m]
13. A particle with a charge of 0.030 C experiences a magnetic force of 1.5 N while
moving at right angles to a uniform magnetic field. If the speed of the charge is
620 m/s, what is the magnitude of the magnetic field the particle passes through?
[0.081 T]
14. An electron moving north encounters a uniform magnetic field. If the magnetic field
points east, what is the direction of the magnetic force on the electron? Explain.
[upward]
15. A straight segment of wire has a length of 25 cm and carries a current of 5.0 A. If the
wire is perpendicular to a magnetic field of 0.60 T, then what is the magnitude of the
magnetic force on this segment of the wire? [0.75 N]
16. Two parallel wires have charges moving in the same direction. Is the force between
them attractive or repulsive?
17. D If a wire is carrying current to the north, draw the directin of the magnetic field
circling the wire using dots and X’s to show the direction
a. The current in the wire is pointed NORTH
b. the current in the wire is pointed EAST
Magnetism p 4
A1 Conceptual Physics
Spring 2013
Magnetism
Chapters 36 & 37
Magnetism & Electromagnetism Lab
SAFETY ALERT: ANY GROUP which spills iron fillings or puts them on the magnet
will get 20 points off for unsafe lab practices.
Use COMPLETE Sentences for full credit.
PROBLEM:
What are the properties of magnets? How do electromagnets
work?
HYPOTHESIS: (5 pts)_________________________________________________________________
MATERIALS:
magnets
iron filings
iron nail
2 Battery
staples
magnetic compass
momentary switch wire
wooden popsicle stick
plastic transparency sheet
container with holes to sprinkle iron filings
PROCEDURE:
Make sure that the plastic transparency sheet is over the
magnet and you sprinkle the iron filings over the plastic.
Pour the iron filings back into the container when you are
finished.
1. Observe the pattern or iron filings when sprinkled over a bar magnet and
sketch the iron filing pattern below. The iron filings follow the magnetic
field lines. (DO NOT JUST scribble or shade everything in. You should see
LIENS)
2. Observe the pattern of iron filings when the same poles of two magnets are
close to each other. Sketch this magnetic field pattern.
3. Observe the pattern of iron filings when opposite poles of two magnets are
close to each others. Sketch this magnetic field pattern.
4. Based on your observations, what is the Law of Magnetic Poles? (attract?
repel?)
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A1 Conceptual Physics
Magnetism
Spring 2013
Chapters 36 & 37
5. Put one bar magnet down on the table and bring a magnetic compass 2 cm
from the end of the North pole. Move the magnetic compass around the bar
magnet keeping it 2 cm away from the magnet itself. Use arrows to sketch
what happens to the needle of the compass.
N
S
You are following the magnetic field made by the magnetic domains.
Record 6-9 In Chart Below
6. Take an iron nail and wrap the wire around the nail five times. Connect to
the momentary switch and battery. Press down the switch for a moment
and see how many staples can be picked up.
7. Wrap the wire around the nail as many times as possible but make sure the
wire touches the nail. Connect to the battery. Press down the switch for a
moment and see how many staples can be picked up.
8. Add a second battery in series. See how that affects the number of staples
that can be picked up.
9. Replace the iron nail with the wooden popsicle stick. Wrap the wire around
it as many times as possible. Make sure all of the wire touches the stick.
Attach the momentary switch and press down the switch for a moment to
see how many staples can be picked up
Problem
#6 – 5 Wraps #7 – Max
#8 – 2 Batteries #9 – Popsicle
Wraps
Stick
# Staples
QUESTIONS & ANALYSIS: MUST use Complete Sentences.
1. In your own words define the following:
a. Magnetic field
b. Domains
c. Electromagnet
d. Law of Magnetic Poles
2. How can you make an electromagnet stronger? Give at least three ways.
3. Sketch the magnetic field around a wire with electricity moving through it.
4. Research and describe the first Right Hand Rule.
CONCLUSION:
Rubric:
Re-answer the original problem on this lab using observations
to support your conclusion. MUST be a paragraph – Minimum of
5 sentences including topic sentence. (15 Points – so be detailed
and complete)
Sketches: 10 pts x 4 = 40 pts
Questions/Definitions 5pts x 8 = 40 pts
Magnetism p 6
Chart: 5 pts
Conclusion: 15 pts
A1 Conceptual Physics
Spring 2013
Magnetism
Chapters 36 & 37
Magnetism Review Sheet
1. Magnetism and Electricity are the same. True / False
2. What are the names of the three metals that can be magnetized?
3. What is the law of Magnetic Poles?
4. What causes a magnetic field ( in general)?
5. What causes the magnetic field in a permanent magnet?
6. There are always ________ pole in a magnet.
7. The geographical north pole of earth is the magnetic ____________ pole.
8. The angle difference between geographic North Pole and Magnetic North Pole is
called ____.
9. Explain two ways to produce a temporary magnet.
10. Where is the field the strongest in a magnet?
11. With what did the iron filings and compass needle line up in the Magnetism Lab?
12. Sketch the domains in a piece of iron before and after it is magnetized.
Before
After
13. Sketch the field lines around the following bar magnet.
N
S
14. What surrounds the Earth and protects us from harmful electromagnetic energy
waves?
15. A __________________ ___________ surrounds a current carrying wire.
16. What do we call a current carrying wire wrapped in consecutive loops?
17. Describe 3 ways an electromagnet can be made stronger.
18. List three technological application for magnets and/or electromagnets.
19. What is the right hand rule?
20. In what direction would the original force be on a positive charge traveling west
through the following field? Draw a vector representing the force’s direction on the
charge in the field.
N
W
E
S
XXXXXXXXX
XXXXXXXXX
XXXXXXXXX
Magnetism p 7
A1 Conceptual Physics
Magnetism
Spring 2013
Chapters 36 & 37
21. In what direction is a negative charge traveling if the magnetic force on it is north
when it enters the following field? Draw a line and arrow through the field
representing the direction the charge is traveling.
N
OOOOOOOO
W
E
OOOOOOOO
S
OOOOOOOO
22. Magnetic field is represented by the variable ____ and measured in ____________
23. Charge is represented with the variable _____ and is measured in __________
24. Magnetic force is measured in _____________ and represented with the variable ______
25. Velocity is measured in _______ and represented with the variable ________
26. Current is represented by the variable ____ and is measured in _______
27. Length of the current carrying conductor is represented with the variable _____ and
measured in ________
28. Two current carrying wires parallel to each other, with current in the same
direction have a(n) ________________ force on each other.
29. Two current carrying wires parallel to each other, with current in opposite
directions have a(n) __________________ force on each other.
30. If a charged particle is travelling parallel to the B field there is _____ magnetic force
on it.
31. If a charged particle is travelling perpendicular to the field it has the _________
magnetic force on it.
32. If an electron with a 1.6 x 10-19 charge traveling east at 100 m/s is pushed down
with a force of 12 N as it enters a magnetic field, what is the magnitude and direction of
the magnetic field? [7.5 x 1017 T, North]
33. If a 5 meter long wire carrying a 5 amp current runs west perpendicularly through
a B field of 2 Teslas pointing north, what is magnitude and direction of the force on the
wire? [50 N, up]
34. A proton, with a charge of +1.6 x 10-19 C, moving east experiences a force of 5.5 x 1025 N upward due to the Earth’s magnetic field. At this location, the field has a magnitude
of 8 x 10-5 T to the north. Find the speed of the particle. [ 0.04 m/s ]
35. A wire 12 m long carries a current of 5 A to the west. If the maximum magnetic
force on the wire at this point is downward (toward Earth) and has a magnitude of 5.0
x 10-2 N, find the magnitude and direction of the magnetic field at this location. [8.3 x
10-4 T North]
36. The magnetic force acting on a wire that is perpendicular to a 1.5 T uniform
magnetic field is 4.4 N. If the current in the wire is 5.0 A, what is the length of the wire
that is inside the magnetic field?
[0.59 m]
37. If the current in a wire 3 meters long is running from North to South perpendicular
to a Magnetic field of 1T and experiences a magnetic force of 9 N, what if the magnitude
of the current? [ 3 A]
Magnetism p 8