April 1967 Popular Electronics
Wax nostalgic about and learn from the history of early electronics. See articles
published October 1954 - April 1985. All copyrights are hereby acknowledged.
Here is a quick test of your graph reading skills. It appeared
in the April 1967 edition of Popular Electronics. I missed #6
- a temporary (hopefully) case of cranial rectumitis on my part.
Maybe you will do better.
Graph Interpretation Quiz
By Robert P. Balin
Today's front-line electronic technician must be able to
interpret readily the various charts and graphs devised by engineers
to convey important information on the electrical characteristics
of circuits as well as of individual components. In addition,
the technician must be thoroughly familiar with the origin and
composition of a variety of unusual as well as standard oscillographic
waveforms. Test your ability to interpret the graphs and waveforms
shown below (1-10) by selecting the most likely meaning, (A)
or (B), from the two possibilities given in each case.
1. The family of plate characteristic
curves for a triode shows that as the plate voltage is increased
the a.c. plate resistance (A) increases or (B) decreases.
2. The distortion seen in this square-wave
test signal indicates that the amplifier being tested is attenuating
the (A) low frequencies or (B) high frequencies.
3. The collector current vs. base current
curve for a transistor indicates that as the base current is
increased the beta (gain) of the transistor (A) increases or
4. This transmitter modulation pattern
indicates that the r.f. carrier is (A) over-modulated or (B)
5. Output curves show that as a transistor's
collector voltage increases, the a.c. output resistance (A)
increases or (B) decreases.
6. Vacuum-tube mutual transconductance
curve indicates that as grid bias is increased mutual transconductance,
Gm, (A) increases or (B) decreases.
7. Of the two load lines, (A) and (B),
shown in the graph at right, which one represents the larger
value of load resistance?
8. The magnetization curve for a transformer
core material shows that as the core goes into saturation its
permeability (A) increases or (B) decreases.
9. The rate of change of a current
depicted by a sine wave is greatest when the current is at its
peak (A), or (B) when it is passing through 0.
10. This frequency response curve for
a tuned transformer indicates that the windings are (A) over-coupled
or (B) under-coupled.
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.
- Test Your
Knowledge of Semiconductors, August 1972
- Ganged Switching Quiz,
- Lamp Brightness Quiz,
Lissajous Pattern Quiz, September 1963
Quizoo, October 1962
Photo Album Quiz, March 1963
Alphabet Quiz, May 1963
- Quiz: Resistive?
Inductive? or Capacitive?, October 1960
Vector-Circuit Matching Quiz, June 1970
Quiz, September 1961
- RC Circuit Quiz,
- Diode Quiz, July
Curves Quiz, February 1963
Electronic Numbers Quiz, December 1962
Conversion Quiz, April 1963
- Coil Function
Quiz, June 1962
Analogy Quiz, August 1960
- Audio Quiz,
Unit Quiz, May 1962
Circuit Quiz, June 1968
on AC Circuit Theory, December 1970
Magnetic Phenomena Quiz, February 1962
Electronics Geography Quiz, April 1970
Menu Quiz, August 1963
Noise Quiz, August 1962
Current Quiz, October 1963
- Electronic Inventors Quiz, November 1963
Function Quiz, January 1962
Measurement Quiz, January 1963
- Vacuum Tube
Quiz, February 1961
- Kool-Keeping Kwiz, June
1 - B The slope of these curves represents the ratio Ip/Ep,
or conductance (the reciprocal of resistance). As the plate
voltage is increased, the slope and conductance also increase,
and the resistance decreases.
2 - A The fundamental and low-frequency components of a square
wave contribute chiefly to the center portion of its flat top.
Thus, if an amplifier under test attenuates the low frequencies,
a dip appears in the center of the square-wave test signal.
3 - B The slope of this curve represents the ratio lc/IB,
or beta, the current gain of a transistor. As the base current
increases, the slope of the curve and beta decrease.
4 - A Overmodulation can reduce an r.f. carrier to zero amplitude
during a period of time as shown by the thin base line through
the modulation envelope.
5 - A The slope of this family of curves indicates changes
in the conductance of the transistor. As the collector voltage
(VCE) is increased, the slope and conductance decrease,
and the resistance increases.
6 - B The slope of this curve represents the ratio Ip/EG,
or mutual conductance (Gm) of this vacuum tube. As the grid
voltage (Eg) is increased, the slope and Gm decrease.
7 - B The slope of a load line represents the conductance
of the load resistance. The load line with the lesser slope
(B) shows a lower conductance, or higher resistance.
8 - B The slope of this curve reflects the ratio B/H, the
permeability of the core material. As the curve goes over the
knee, the slope and permeability both decrease.
9 - B At its peak amplitude, a sine wave changes from one
finite value to another, but as it passes through zero it changes
from a finite value to zero, resulting in an infinite percent
10 - A When the windings of a tuned air-core transformer
are overcoupled, a dip is produced in the center of an otherwise
single-peaked frequency-response curve, and two new resonant
peaks occur at slightly higher and lower frequencies.
Posted July 26, 2012