May 1966 Popular Electronics
Table of Contents
Wax nostalgic about and learn from the history of early electronics. See articles
published October 1954 - April 1985. All copyrights are hereby acknowledged.
The circuit drawings in this Series
Circuit Quiz are a little hard to read in a few places because the original page used
light red on top of a gray background. The magic of image processing did a pretty good
job of cleaning them up to where you shouldn't have any trouble reading them. This quiz
from Robert Balin appeared in the April 1966 issue of Popular Electronics. It
is one of the easier, so don't tell anyone if you score less than 100% ;-)
Series Circuit Quiz
By Robert P. Balin
Experimenters often have to connect similar electronic components - resistors, capacitors,
coils, etc. - in series to obtain a desired value or effect. This deceptively simple
task requires an understanding of the basic operating principles of the components. See
how many of these True /·False questions you can answer correctly by first working out
1. If two capacitors are connected in series
across a voltage source, the smaller one will charge up to the larger proportion of the
6. If two voltmeters, each set on the same
scale, are in series across a voltage source, the one with the higher ohms/volt rating
gives the greater deflection.
2. If two lamps of equal voltage and wattage
rating are connected in series across a power source, each will deliver one-half of its
7. If the filaments of a 6V6 and a 12SQ7
electron tube are wired in series, the tubes will operate satisfactorily when connected
across an 18-volt source.
3. If two s.p.s.t. switches are connected
in series with a battery and a lamp. the arrangement may be considered the same as an
"OR" logic circuit.
8. Two 100-ohm resistors placed across a
battery having an internal resistance of 100 ohms dissipate twice as much power as one
of the external resistors.
4. If a 3-ohm, 2-watt speaker and a 6-ohm,
1-watt speaker are connected in series, the 1-watt speaker will deliver twice as much
power as the 2-watt speaker .
9. If the two secondary windings of a transformer
are in series as shown, the output voltage is the sum of the individual secondary coil
5. If two dry cells of equal current and
voltage rating are connected in series across a load, the current-handling capability
of the circuit is increased twofold.
10. If a 500-ohm. 5-watt resistor and a
500-ohm, 10-watt resistor are in series across a 100-volt source, they are considered
equal to a 1000-ohm, 15-watter.
1. True. With unequal capacitors in series, the voltage across each capacitor is inversely
proportional to its capacitance. This is shown by the formula E = Q/C, where Q, the number
of electrons moving in the circuit, is the same for both capacitors.
2. False. Since the lamps have the same resistance, the applied voltage and the current
in the circuit will be reduced by a factor of one-half. And, since P = EI, each lamp
will operate at one-fourth its rated power.
3. False. As shown, S1 and S2 must both be closed before the lamp will light, so that
the arrangement forms an "AND" circuit.
4. True. Each speaker will receive the same amount of current from the source, and,
since P = I2Z, the power developed will be a function of the voice coil impedance,
Z. The 6-ohm speaker produces twice the power of the 3-ohm speaker for the same input.
5. False. Although the total voltage across the two cells in series equals the sum
of the individual cell voltage, like two similar fuses in series, the current-handling
capability of the circuit is not altered.
6. True. Voltmeter sensitivity is a product of its ohms/volt rating and the scale
setting. On the 5-volt scale, the resistance of the 20,000 ohms/volt meter is 100,000
ohms, while the resistance of the 10,000 ohms/ volt meter is 50,000 ohms. The voltage
drop across the 20,000 ohms/volt meter is greater than the drop across the other meter,
giving a greater deflection.
7. False. From the tube manual, a 6V6 draws 450 ma, while a 12SQ7 draws only 150 ma.
From Ohm's law, the filament resistances are, respectively, 13 ohms and 80 ohms. Therefore,
the current in the series circuit would be approximately 200 ma., placing 2.6 volts across
the 6V6, and more than 15 volts across the 12SQ7.
8. False. Since P = I2R, the reduced current resulting from two resistors
instead of one has a greater effect on the power dissipation than does an increase in
9. True. The polarity marks indicate that the secondary voltages are in phase and
are series-aiding. Thus, the output voltage is the sum of the two secondary voltages.
10. False. Since a current of 100 ma. flows in the circuit, the power dissipated by
each resistor is 5 watts (P = EI) for a total dissipation of 10 watts. If a 1000-ohm
resistor is substituted for the two 500-ohm units, the power dissipation remains at 10
watts (by the same formula).
Posted April 9, 2018
Popular Electronics published many quizzes over the years
- some really simple and others not so simple. Robert Balin created many of the quizzes.
This is a listing of all I have posted thus far.
- TV Trouble Quiz,
- Electronics History Quiz,
- Scope-Trace Quiz,
March 1965 Popular Electronics
Circuit Analogy Quiz, April 1973
Your Knowledge of Semiconductors, August 1972
- Ganged Switching
Quiz, April 1972
- Lamp Brightness
Quiz, January 1969
- Lissajous Pattern Quiz, September 1963
Quizoo, October 1962
- Electronic Photo Album Quiz, March 1963
- Electronic Alphabet Quiz, May 1963
- Quiz: Resistive?
Inductive? or Capacitive?, October 1960
- Vector-Circuit Matching Quiz, June 1970
Quiz, September 1961
- RC Circuit
Quiz, June 1963
- Diode Quiz,
- Electronic Curves Quiz, February 1963
- Electronic Numbers Quiz, December 1962
- Energy Conversion Quiz, April 1963
Function Quiz, June 1962
Series Circuit Quiz,
Electrochemistry Quiz, March 1966
- Electronic Analogy
Quiz, November 1961
Coupling Quiz, August 1973
- Electronics Analogy Quiz, August 1960
- Audio Quiz,
Unit Quiz, May 1962
Capacitor Circuit Quiz, June 1968
- Quiz on AC Circuit Theory, December 1970
- Magnetic Phenomena Quiz, February 1962
- Electronics Geography Quiz, April 1970
Electronic Menu Quiz, August 1963
- Electronic Noise Quiz, August 1962
- Electronic Current Quiz, October 1963
- Electronic Inventors Quiz, November 1963
Function Quiz, January 1962
- Electronic Measurement Quiz, January 1963
Tube Quiz, February 1961
- Kool-Keeping Kwiz, June