Download PROBLEM SET Magnetism and Induction

MYIB/Honors Physics
Myers Park High School
Problem Set: Magnetism and Induction
A. Magnetic Fields and Magnetic Forces
1. Draw the magnetic Field Lines around the bar magnet shown below.
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2. Draw the magnetic field lines between the poles of the magnets shown below.
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3. Draw the magnetic field lines around a straight section of wire carrying a current horizontally left.
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4. Draw the magnetic field lines around a straight wire carrying current that is moving directly
towards you.
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5. Determine the magnitude and direction of the force acting on a proton traveling 3.58 × 106 m/s
horizontally west in a vertically upward magnetic field of strength 1.30 T.
6. An electron with a speed of 1.80 × 106 m/s enters a 0.250 T magnetic field at an angle of 90°.
a. What is the magnitude of the force?
b. If the electron is moving north in a horizontal plane and the magnetic field is directed
vertically downward, what direction will the electron be deflected?
7. Indicate the direction a proton will be deflected in the situations below. B is the magnetic field
and v represents the direction the proton is moving.
a)
B
.
v
b)
XB
v
c) v
X
d)
B
B
e)
v
f)
B
v
.
v
B
8. Electric current is flowing through a copper wire.
a. What is the force per meter on the wire when carrying 9.8 A of current and is
inserted perpendicularly to a 0.80 T magnetic field?
b. What is the force if the angle between the wire and the magnetic field is 45°?
MYIB/Honors Physics
Myers Park High School
Problem Set: Magnetism and Induction
9. A wire 1.5 m in length is carrying 6.5 A of current is oriented horizontally. At this point
on the Earth’s surface, the dip angle of the Earth’s magnetic field makes an angle of 40°
to the wire. What is the magnitude of the force on the wire due to the Earth’s magnetic
field of 5.5 × 10-5 T at this point?
10. How much current is flowing in a wire 4.2 m long if the maximum force on it is 0.900 N
when places in a uniform 0.0800 T field?
11. The force on a wire carrying 25.0 A is a maximum of 4.14 N when placed between the
poles of a magnet. If the pole faces are 22 cm in diameter, what is the approximate
strength of the magnetic field?
12. Compare and contrast a meter and a motor.
B. Electromagnets, Transformers, and Electromagnetic Induction
13. Draw a step down transformer using the diagram of the core below.
Primary Coil (in)
Secondary Coil (out)
14. To induce current in a loop of wire, there must be a(n) _________ magnetic field inside
the loop.
a. increasing
b. decreasing
c. changing
15. Faraday determined that if the number of loops in a coil of wire increases, the ________
induced in the wire by a changing magnetic field will ________.
16. A transformer with a turns ratio of 13:1 (primary:secondary) is used in a wall socket
(voltage 120 V) as part of a battery recharging unit.
a. Is the transformer a step up or step down?
b. What is the voltage supplied to the recharging unit?
17. A step up transformer has a primary coil consisting of 200 turns and a secondary coil
consisting of 3000 turns. The primary coil is supplied with an effective voltage of 90.0 V.
a. What is the voltage in the secondary coil?
b. If the current in the secondary coil is 2.0 A, what is the current in the primary coil?
18. A step down transformer has 7500 turn in the primary coil and 125 turns in the secondary
coil. The voltage across the primary coil is 7200 V. If the current in the secondary coil is
36 A, what is the current in the primary coil?
MYIB/Honors Physics
Myers Park High School
Problem Set: Magnetism and Induction
19. The rectangular loop of wire shown in the diagram is pushed into the magnetic field
which points inward as shown. In what direction is current induced?
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20. The north pole of a magnetic is inserted into a coil of wire as shown in the diagram. In which
direction will current flow through the resistor R?
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R
1. See Instructor
2. See Instructor
3. See Instructor
4. See Instructor
5. 7.45 x 10-13 N
North
6. a) 7.2 x 10-14 N
b) East
8. a) 7.84 N
b) 5.54 N
9. 3.45 x 10-4 N
10. 2.68 A
7. a) right b) right
c) down d) out of
the page
e) zero f) up
11. 0.753 T
12. See Instructor
13. c. changing
14. voltage/emf (current);
increase
15. a. step down
b. 9.23 V
16. a. 1350 V
b. 30 A
17. 0.6 A
18. counterclockwise
19. right to left
12. See Instructor