28)
If the load resistance decreases in a zener regulator, the series current
28)
A)
stays the same.
B)
equals the source voltage divided by the series resistance.
C)
decreases.
D)
increases.
Answer:
A
Explanation:
A)
B)
C)
D)
29)
Refer to (a) in the figure above. The symbol is for
29)
A)
a zener diode.
B)
an LED.
C)
a Schottky diode.
D)
a photodiode.
E)
a tunnel diode.
Answer:
B
Explanation:
A)
B)
C)
D)
E)
30)
Quantum dot filters are used to
30)
A)
increase the blue content of an LED lighting system.
B)
make white LEDs look more like incandescent lights.
C)
focus LEDs for fiber optic systems.
D)
limit bandwidth.
Answer:
B
Explanation:
A)
B)
C)
D)
31)
The band gap of a quantum dot is dependent on
31)
A)
the size of the dot.
B)
its color.
C)
its frequency.
D)
the dot polarity.
Answer:
A
Explanation:
A)
B)
C)
D)
8
32)
If the load resistance decreases in a zener regulator, the zener current
32)
A)
increases.
B)
equals the source voltage divided by the series resistance.
C)
stays the same.
D)
decreases.
Answer:
D
Explanation:
A)
B)
C)
D)
33)
To display the digit 8 in a seven–segment indicator
33)
A)
G must be off.
B)
only F must be on.
C)
only C must be lighted.
D)
all segments must be on.
Answer:
D
Explanation:
A)
B)
C)
D)
34)
Refer to the figure above. If Vin increases, VR will
34)
A)
decrease.
B)
increase.
C)
remain the same.
D)
Unable to determine.
Answer:
B
Explanation:
A)
B)
C)
D)
35)
When a zener diode is forward–biased, it
35)
A)
operates like a rectifier diode.
B)
emits visible light.
C)
exhibits a voltage drop of VZ+ 0.7 V.
D)
conducts no current.
Answer:
A
Explanation:
A)
B)
C)
D)
9
36)
An LED is forward–biased. The diode should be on, but no light is showing. A possible problem
might be
36)
A)
none; the diode should be off if forward–biased.
B)
that the series resistor is too small.
C)
that the diode is open.
D)
that the power supply voltage is too high.
Answer:
C
Explanation:
A)
B)
C)
D)
37)
A 6.2 V zener is rated at 1 watt. The maximum safe current the zener can carry is approximately
37)
A)
1.61 A.
B)
16.1 mA.
C)
161 mA.
D)
1.61 mA.
Answer:
C
Explanation:
A)
B)
C)
D)
38)
Which of the following has a negative–resistance region?
38)
A)
LED
B)
Tunnel diode
C)
Rectifier diode
D)
Schottky diode
Answer:
B
Explanation:
A)
B)
C)
D)
39)
Typically, the maximum VF for an LED is between
39)
A)
0 V and 0.7 V.
B)
1.2 V and 3.2 V.
C)
3.2 V and 10 V.
D)
1 V and 1.4 V.
Answer:
B
Explanation:
A)
B)
C)
D)
40)
What is true about the breakdown voltage in a zener diode?
40)
A)
It destroys the diode.
B)
It occurs only in the forward region.
C)
It decreases when current increases.
D)
It is approximately constant.
Answer:
D
Explanation:
A)
B)
C)
D)
10
41)
The best type of diode to use in a tuning circuit is
41)
A)
a varactor.
B)
an LED.
C)
a Schottky diode.
D)
a Gunn diode.
Answer:
A
Explanation:
A)
B)
C)
D)
42)
Refer to (e) in the figure above. The symbol is for
42)
A)
a zener diode.
B)
an LED.
C)
a Schottky diode.
D)
a photodiode.
E)
a tunnel diode.
Answer:
C
Explanation:
A)
B)
C)
D)
E)
43)
A tunnel diode has ________ characteristic(s).
43)
A)
a linear
B)
a negative resistance
C)
extremely light doping
D)
an extremely wide depletion region
Answer:
B
Explanation:
A)
B)
C)
D)
11
44)
Refer to (d) in the figure above. The symbol is for
44)
A)
a zener diode.
B)
an LED.
C)
a Schottky diode.
D)
a photodiode.
E)
a tunnel diode.
Answer:
E
Explanation:
A)
B)
C)
D)
E)
45)
A photodiode is normally
45)
A)
used to regulate voltage.
B)
reverse–biased.
C)
forward–biased.
D)
not biased.
Answer:
B
Explanation:
A)
B)
C)
D)
46)
LED color is determined by
46)
A)
the material used for the incandescent filament.
B)
the impurities added during doping to control wavelength.
C)
the applied LED voltage.
D)
the LED current.
Answer:
B
Explanation:
A)
B)
C)
D)
TRUE/FALSE. Write ‘T’ if the statement is true and ‘F’ if the statement is false.
47)
The regulating ability of a zener diode depends upon its ability to operate in a breakdown
condition.
47)
Answer:
True
False
Explanation:
12
48)
Dark current is the amount of thermally generated forward current in a photodiode in the absence
of light.
48)
Answer:
True
False
Explanation:
49)
LED lights are 20 times more efficient than standard incandescent lights.
49)
Answer:
True
False
Explanation:
13