March 1968 Popular Electronics
Table of Contents
Wax nostalgic about and learn from the history of early electronics. See articles
from
Popular Electronics,
published October 1954 - April 1985. All copyrights are hereby acknowledged.
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Here's one last thing
to do before you leave work for the weekend. This "Polarity Quiz" by Robert
Balin appeared in a 1968 issue of Popular Electronics. If you know your
left- and right-hand rules for magnetism and induction, then a 100% score is
practically guaranteed... provided you also are a whiz at diode and meter
connections. Since the author did not do so, I provided brief explanations for
the answers at the bottom of the page. When applying the hand-rules, assume
conventional current (flow from more positive to more negative), not electron
current.
Polarity Quiz
By Robert P. Balin
Electronics technicians and hobbyists must
be able to determine the polarity of a generated voltage or voltage drop to really
understand how a circuit operates. They must also be able to determine the polarity
of the supply voltage to be applied to a circuit, and how to install correctly a
polarized component such as a diode, meter, or electrolytic capacitor. Test your
ability to handle polarity problems correctly by selecting either "positive" or
"negative" in each of the following statements.
1) To produce a north pole at the top of this electromagnet, the (positive __ negative __
) d.c. supply terminal must be applied at point A.
2) When the permanent magnet is
dropped through the coil, the polarity of the voltage generated at point A will
be (positive __ negative __ ) with respect to point B.
3) The direction of the electron flow through RL will be indicated when
the polarity of the instantaneous voltage at point A is (positive __ negative __ ) with respect to point B.
4) Voltage at point
A of this rectifier is (positive __ negative __ ) with respect to ground.
5) To bypass the emitter resistor properly, connect the (positive __ negative __ ) terminal of the
electrolytic capacitor to the emitter.
6) To bias the collector circuit of this transistor
amplifier properly, a battery must be inserted so that its (positive __ negative __ )
terminal is connected to the collector?
7) The nonsymmetrical waveform appearing
on this d.c. scope indicates that most of the signal has a (positive __ negative __ )
polarity.
8) For the plate current meter in this circuit to deflect correctly,
the plate lead must be connected to the (positive __ negative __ ) terminal of the ammeter.
9) The polarity of the voltage at point A of this bridge circuit will be (positive __ negative __ )
with respect to point B.
10) The voltage at point A is (positive __ negative __ ) with
respect to ground.
<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.
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-
Elementary
Radio Quiz - December 1947 Radio-Craft
- Hi-Fi
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
- Electronic
Switching Quiz - October 1967 Popular Electronics
- Electronic
Angle Quiz - September 1967 Popular Electronics
- International
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
1953 QST
- TV Trouble Quiz,
July 1966 Popular Electronics
- Electronics History Quiz,
December 1965 Popular Electronics
- Scope-Trace Quiz,
March 1965 Popular Electronics
-
Electronic
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
- Electronic
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
- Inductance
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
-
Television
I.Q. Quiz - October 1948 Radio & Television News
- Amplifier Quiz
Part I - February 1964 Popular Electronics
- Semiconductor
Quiz - February 1967 Popular Electronics
- Unknown
Frequency Quiz - September 1965 Popular Electronics
- Electronics
Metals Quiz - October 1964 Popular Electronics
- Electronics
Measurement Quiz - August 1967 Popular Electronics
- Meter-Reading
Quiz, June 1966 Popular Electronics
- Electronic
Geometry Quiz, January 1965 Popular Electronics
- Electronic
Factor Quiz, November 1966 Popular Electronics
- Electronics
Math Quiz, November 1965 Popular Electronics
- Series Circuit
Quiz, May 1966 Popular Electronics
- Electrochemistry
Quiz, March 1966 Popular Electronics
- Biz
Quiz: Test Your Sales Ability - April 1947 Radio News
- Electronic
Analogy Quiz, November 1961 Popular Electronics
- Electronic
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
- Capacitor
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
- Electronic
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
Post
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Polarity Quiz Answers
1) Positive (per the right-hand rule of magnetism)
2) Negative (per Faraday's left-hand rule of induction)
3) Positive (note 180° phase shift through winding)
4) Negative (diodes conduct during negative half-cycle)
5) Negative (PNP transistor has p-type base and n-type emitter, looks
like question 4 circuit)
6) Positive (NPN transistor gets positive collector wrt base)
7) Negative (waveform shifted downward toward negative)
8) Negative (left side must be more negative than right side connected
to B+ supply)
9) Negative (VA = 35/80 = 0.4375, VB = 30/50 =
3/5 = 0.6; VA < VB)
10) Negative (VA = -5 + 30/[30+80]*[5+10] = -5 + 4.0901 =
-0.9091)
Posted August 28, 2020
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