Download 22 Review

Physics Pre-AP
Review CH 21-22
Name: ____________________
Date: _______ Period: ___
1. If the north pole of one magnet is brought near the south pole of another magnet, the
poles will _____.
a. Attract each other
b. Repel each other
c. Not interact with each other at all
2. If you break a bar magnet in half, each half _____.
a. Contains one magnetic pole
b. Becomes a bar magnet with two poles
c. Becomes unmagnetized
3. If you put a small compass in a magnetic field, the compass will _____.
a. Swing randomly
b. Line up in a direction perpendicular to the magnetic field lines
c. Line up in a direction parallel to the magnetic field lines
d. Seek electrical charge concentrations
4. Magnetic field strength is _____.
a. Strongest close to a magnet
b. Strongest far from a magnet
c. Constant everywhere around a magnet
5. Magnetic domains are _____.
a. Clusters of atoms randomly aligned
b. Blocks of materials
c. Regions that may or may not be magnetized
d. Regions of atoms magnetically aligned
6. Permanent magnets can be made by _____.
a. Stroking material containing iron with a magnet
b. Placing a piece of iron in a strong magnetic field
c. Placing a piece of iron near a strong electromagnet
d. All of the above
e. None of the above
7. The reason a magnet can attract an unmagnetized nail is that _____.
a. Nails become permanently magnetized in a magnetic field.
b. Nails become temporarily magnetized in a magnetic field
c. Nails are really magnetized
d. A magnet cannot attract anything that is not also magnetized.
8. When current passes through a wire, a magnetic field is created around the wire only if
the _____.
a. Current comes from a battery
b. Current makes a complete stop
c. Wire is absolutely straight
d. Wire is curved in a loop
e. Nonsense, a magnetic field is always created around a current carrying wire.
9. In order to make an electromagnet, you need a _____.
a. Battery, some wire, and a nail
b. Battery, a nail, and a magnet
c. Magnet, a nail, and some wires
d. Loop of wire, contacts and a battery
e. None of the above
10. A galvanometer can also be made into _____.
a. An ammeter
c. Both a and
b. A voltmeter
b
11. The magnetic pole in the Northern Hemisphere is located _____.
a. In Alaska
b. In Canada
c. Just north of the United States
d. None of the above
12. Which geographic pole of the earth is nearest the magnetic north pole of the earth?
a. North pole
b. South pole c. both a and b
13. If a compass is moved from the Northern Hemisphere to the Southern Hemisphere, its
magnetic needle will _____.
a. Change direction by 180 degrees
b. Not change at all
c. Change direction by 90 degrees
d. None of the above
14. Magnetic field lines surrounding a magnet are conventionally drawn _____.
a. From north to south
b. From south to north
c. Either way
15. Electric current can best be induced in a wire by _____.
a. Moving the wire up and down
b. Setting the wire near a magnet
c. Moving a magnet up and down near the wire
d. Rotating the wire
e. None of the above
16. A magnet is moved in and out of a coil of wire connected to a high resistance voltmeter.
If the number of coils doubles, the induced voltage _____.
a. Quadruples
d. Halves
e. None of the above
b. Doubles
c. Is the same
17. The phenomenon of inducing voltage by changing the magnetic field around a conductor
is called _____.
a. Generated voltage
b. Faraday’s induction
c. Electromagnetic radiation
d. Transformer induction
e. Electromagnetic induction
18. A device that uses two coils around an iron core to change the voltage across a circuit is
called a ____.
a. Voltmeter
d. Generator
b. Diode
e. Motor
c. Transformer
19. A step up transformer _____.
a. Decreases voltage
b. Increases voltage
c. Doesn’t change voltage at all
20. The primary coil of a transformer has 100 turns on it and the secondary coil as 0 turns on
it. This is _____.
a. A step up transformer
b. A step down transformer
c. A transforming robot-more than meets the eye.
21. Who invented the generator?
a. Hans Christian Oersted
c. Nikola Tesla
b. William Gilbert
d. Michael Faraday
22. Who discovered the principle of induction?
a. Hans Christian Oersted
c. Nikola Tesla
b. William Gilbert
d. Michael Faraday
23. Who discovered that a current carrying wire has a magnetic field?
c. Nikola Tesla
a. Hans Christian Oersted
b. William Gilbert
d. Michael Faraday
24. Who invented the transformer?
a. Hans Christian Oersted
c. Nikola Tesla
b. William Gilbert
d. Michael Faraday
25. Lenz’s Law states that
a. An induced emf will always enhance the change in flux that induced it.
b. An induced emf will always oppose the change in flux that caused it.
c. An induced flux will always oppose a change in the magnetic field.
d. An induced flux will always oppose a change in emf.
26. The primary coil to a transformer has 1,000, and is connected to a 120 V source. What
number of turns in the secondary will produce 12 V?
V2 N 2 12
N


 2  N 2  100
V1 N1 120 1000
27. A step up transformer has 100 turns on its primary and 500 turns on its secondary. When
the primary is supplied with an alternating current at 120 V, what is the voltage across the
secondary?
V2 N 2 V2 500



 V2  600V
V1 N1 120 100
28. A proton moves at a speed of 2.0 x 107 m/s north to a magnetic field with a magnitude of
0.10 T pointed down. Find the magnitude and direction of the force acting on the proton.


Fmag  Bqv  0.10 1.602 10 19 2.0 107  3.2 10 13 N
Direction
X
X
vX
X
X
X
F
X
X
X
X
X
X
29. An electron moves at 5.5 x 107 m/s east. If the particle experiences a magnetic field of
1.7 x 10-6 T north, find the magnitude and direction of the acceleration of the electron.
Fmag  Bqv  1.7  10 6  1.602  10 19  5.5  10 7 
1.5  10 17 N
 1.644  1013 m s 2 Up
31
9.11  10
Direction (electron – left hand)
B
v
30. A 6.0 m wire carries a current of 7.0 A upward. A magnetic force of 7.0 x 10-6 N, west
acts on the wire. Find the magnitude and direction of the magnetic field producing the
force. What is the field strength of the magnetic field created by the wire 1 m away?
Fmag  BIl 
 I
7.0  10 6
4  10 7  7.0
 1.7  10 7 T  o 
 1.4  10 6
7.0  6.0
2r
2 (1)
Note: The wire is coming out of the page (up)
B
F