Magnetic Phenomena Quiz
February1962 Popular Electronics
If terms like 'magnetostriction,'
mu-metal,' and 'D-ring' arouse your technostimulus receptors, then this quiz on magnetics
should be just what you've been waiting for. It appeared in a 1962 edition of Popular
electronics, but the principles therein have not changed since then. I must admit that
I had never given thought to the orientation in which bar magnets should be stored when
in close proximity to each other.
Wax nostalgic about and learn from the history of early electronics. See articles
published October 1954 - April 1985. All copyrights are hereby acknowledged.
Magnetic Phenomena Quiz
By Robert P. Balin
Neither magnets nor magnetism are mysteries to the experimenter. But this quiz will
test your knowledge of the basic principles of magnetic phenomena. Mark each statement
"True" or "False" and check your answers at the bottom.
||1 - The north pole of a compass points to the earth's north
2 - If the separation between two unlike magnetic poles is reduced
by half, the attraction between them will become four times as great.
3 - If a compass is placed beneath a wire passing electrons from
A to B, its north pole will point to the right.
4 - Bar magnets should be stored by placing them so that like
poles are side by side.
5 - There is no insulator for magnetic fields. Some metals
simply offer more resistance to magnetism than others.
||6 - A "D-ring" is usually found on d.c. electromagnetic relay
7 - When a nickel-iron rod is magnetized, it will grow shorter in length.
8 - The electromagnet shown here will have its north pole located at the top of the coil.
9 - An electron passing through the deflection yoke magnetic field and out of the page
will be deflected to the right.
10 - A "keeper" is placed across the poles of a horseshoe magnet
to prevent the magnet's field from passing through nearby ferrous objects.
See answers below.
Quizzes from vintage electronics magazines such as Popular
Electronics, Electronics-World, QST, and Radio News were published
over the years - some really simple and others not so simple. Robert P. Balin
created most of the quizzes for Popular Electronics. This is a listing
of all I have posted thus far.
Radio Quiz - December 1947 Radio-Craft
Quiz - October 1955 Radio & Television News
- Electronics Physics
Quiz - March 1974 Popular Electronics
- A Baffling Quiz
- January 1968 Popular Electronics
- Electronics IQ
Quiz - May 1967 Popular Electronics
- Plug and Jack
Quiz - December 1967 Popular Electronics
Switching Quiz - October 1967 Popular Electronics
Angle Quiz - September 1967 Popular Electronics
Electronics Quiz - July 1967 Popular Electronics
- FM Radio
Quiz - April 1950 Radio & Television News
- Bridge Circuit
Quiz -December 1966 Popular Electronics
- Diode Function
Quiz - August 1965 Popular Electronics
- Diagram Quiz,
August 1966 Popular Electronics
- Quist Quiz - November
- TV Trouble Quiz,
July 1966 Popular Electronics
- Electronics History Quiz,
December 1965 Popular Electronics
- Scope-Trace Quiz,
March 1965 Popular Electronics
Circuit Analogy Quiz, April 1973
Test Your Knowledge of Semiconductors, August 1972 Popular Electronics
- Ganged Switching
Quiz, April 1972 Popular Electronics
- Lamp Brightness
Quiz, January 1969 Popular Electronics
- Lissajous Pattern Quiz, September 1963 Popular Electronics
Quizoo, October 1962 Popular Electronics
- Electronic Photo Album Quiz, March 1963 Popular Electronics
- Electronic Alphabet Quiz, May 1963 Popular Electronics
- Quiz: Resistive?
Inductive? or Capacitive?, October 1960 Popular Electronics
- Vector-Circuit Matching Quiz, June 1970 Popular Electronics
Quiz, September 1961 Popular Electronics
- RC Circuit Quiz,
June 1963 Popular Electronics
- Diode Quiz, July
1961 Popular Electronics
- Electronic Curves Quiz, February 1963 Popular Electronics
- Electronic Numbers Quiz, December 1962 Popular Electronics
- Energy Conversion Quiz, April 1963 Popular Electronics
- Coil Function
Quiz, June 1962 Popular Electronics
Co-Inventors Quiz - January 1965 Electronics World
"-Tron" Teasers Quiz - October 1963 Electronics World
- Polarity Quiz
- March 1968 Popular Electronics
I.Q. Quiz - October 1948 Radio & Television News
- Amplifier Quiz
Part I - February 1964 Popular Electronics
Quiz - February 1967 Popular Electronics
Frequency Quiz - September 1965 Popular Electronics
Metals Quiz - October 1964 Popular Electronics
Measurement Quiz - August 1967 Popular Electronics
Quiz, June 1966 Popular Electronics
Geometry Quiz, January 1965 Popular Electronics
Factor Quiz, November 1966 Popular Electronics
Math Quiz, November 1965 Popular Electronics
- Series Circuit
Quiz, May 1966 Popular Electronics
Quiz, March 1966 Popular Electronics
Quiz: Test Your Sales Ability - April 1947 Radio News
Analogy Quiz, November 1961 Popular Electronics
Coupling Quiz, August 1973 Popular Electronics
- Electronics Analogy Quiz, August 1960 Popular Electronics
- Audio Quiz, April
1955 Popular Electronics
- Electronic Unit
Quiz, May 1962 Popular Electronics
Circuit Quiz, June 1968 Popular Electronics
- Quiz on AC Circuit Theory, December 1970 Popular Electronics
- Magnetic Phenomena Quiz, February 1962 Popular Electronics
- Electronics Geography Quiz, April 1970 Popular Electronics
Menu Quiz, August 1963 Popular Electronics
- Electronic Noise Quiz, August 1962 Popular Electronics
- Electronic Current Quiz, October 1963 Popular Electronics
- Electronic Inventors Quiz, November 1963 Popular Electronics
- Resistor Function
Quiz, January 1962 Popular Electronics
- Electronic Measurement Quiz, January 1963 Popular Electronics
- Vacuum Tube Quiz,
February 1961 Popular Electronics
- Kool-Keeping Kwiz, June
1970 Popular Electronics
- Find the Brightest
Bulb Quiz, April 1960 Popular Electronics
Where Do the Scientists Belong? - Feb 19, 1949 Saturday Evening
Magnetic Quiz Answers
1 TRUE. The north pole of a compass points
to the earth's north magnetic pole which is actually the south pole of a large magnet
inside the earth.
2 TRUE. The force of attraction between unlike magnetic poles
varies inversely as the square of the distance between them.
3 TRUE. The north
pole of a compass always indicates the direction of the magnetic field in which it lies.
To determine the direction of the magnetic field, grasp the wire with your left hand
with the thumb in the direction of electron flow, from A to B. Your fingertips will point
in the direction of the magnetic field.
4 FALSE. Bar magnets should be stored
so that opposite poles lie adjacent to each other. The magnetic field from each bar will
then have a closed magnetic circuit lying entirely within the bars themselves. Hence,
the magnetic fields are least likely to go into nearby metallic objects.
There are no materials which resist magnetic fields. However, magnetic shields made of
high-permeability materials such as mu-metal are used to bypass magnetic fields around
the devices to be isolated from the effects of the magnetic fields.
The D-ring is a shorted turn of copper used on a.c. relay coils to prevent armature chattering.
When the magnetic field set up by the coil starts to collapse on alternate half cycles,
a circulating current in the D-ring builds up a magnetic field which holds the contacts
7 TRUE. This is the principle of "magnetostriction" used in ultrasonic
transducers for sonar and in ultrasonic cleaning devices.
8 TRUE. Electrons will
enter the coil from the bottom and exit at the top of the coil. Grasp the coil with your
left hand with the fingers wrapped in the direction of the electron flow. Your thumb
will point to the north pole.
9 FALSE. Use your left hand to determine the magnetic
field around a moving electron. The thumb points in the direction of electron flow and
the curled fingers point in the direction of its magnetic field. Hence, the electron
coming out of the page will have a clockwise field around it. The magnetic field to the
right of the electron will have the same direction as the field of the deflection coil.
Since magnetic lines which have the same direction repel each other, the electron experiences
a force to the left.
10 TRUE. Almost all of the magnet's magnetic lines of force
will pass through the soft iron bar. The "keeper" is usually employed when storing permanent
magnets in order to preserve the magnetic strength.
Posted June 12, 2013