問題一覧
1
Which of the following types of solder is best for radio and electronic use?
Select one:
a. Silver solder
b. Rosin-core solder
c. Aluminum solder
d. Acid-core solder
b
2
A series connected C −R circuit is suddenly connected to a d.c. source of V
volts. Which of the statements is false?
Select one:
a. The initial current flowing is given by V/R
b. The current grows exponentially
c. The final value of the current is zero
d. The time constant of the circuit is given by RC
b
3
Why is a pull-up resistor needed when connecting TTL logic to CMOS logic?
Select one:
a. To decrease the output LOW voltage
b. To increase the output HIGH voltage
c. To decrease the output HIGH voltage
d. To increase the output LOW voltage
b
4
A nickel-cadmium cell has an operating voltage of about ____ volts.
Select one:
a. 1.25
b. 1.5
c. 2.1
d. 1.4
a
5
According to Gauss' law for magnetism, magnetic field lines:
Select one:
a. start at south poles and end at north poles b. form closed loops
c. start at both north and south poles and end at infinity
d. start at north poles and end at south poles
b
6
Which of the following instruments would be best for checking a TTL logic
circuit?
Select one:
a. Continuity tester
b. DMM
c. Logic probe
d. VOM
c
7
What is an L-network?
Select one:
a. A network consisting of an inductor and a capacitor.
b. A "lossy" network.
c. A low power Wi-Fi RF network connection. d. A network formed by joining two low pass filters.
a
8
When examining the frequency response curve of an RC low-pass filer, it
can be seen that the rate of roll-off well above the cutoff frequency is
_______.
Select one:
a. 20 dB/decade
b. 6 dB/octave
c. Both 6 dB/octave and 20 dB/decade
d. 6 dB/decade
c
9
Iron, rather than copper, is used in the core of transformers because iron:
Select one:
a. Has a greater resistivity.
b. Can withstand a higher temperature.
c. Makes a good permanent magnet.
d. Has a very high permeability.
d
10
When a pulsating dc voltage is applied as an input to the primary of a
transformer, the output from the secondary contains:
Select one:
a. a stepped up or down version of pulsating dc voltage.
b. only the steady dc component of the input signal
c. only the ac component of the input signal.
d. None of the choices.
c
11
In normal operation, a p-n-p collector connected in common-base
configuration has:
Select one:
a. the collector at a lower potential than the emitter
b. the base at a higher potential than the emitter
c. the emitter at a lower potential than the base
d. the collector at a higher potential than the emitte
a
12
In normal operation, the junctions of an n-p-n transistor are:
Select one:
a. base-collector forward biased and base emitter reverse biased
b. base emitter forward biased and base collector reverse biased
c. both reverse biased
d. both forward biased
b
13
What waveform would appear on the voltage outputs at the collectors of
an astable multivibrator, common-emitter stage?
Select one:
a. Sawtooth wave.
b. Half-wave pulses.
c. Sine wave.
d. Square wave.
d
14
Which of the following statements is false?
Select one:
a. The national standard phase sequence for a three-phase supply is
R, Y, B.
b. For the same power, loads connected in delta have a higher line
voltage and a smaller line current than loads connected in star.
c. AC may be distributed using a single-phase system with two wires, a
three-phase system with three wires or a three-phase system with four
wires.
d. When using the two-wattmeter method of power measurement the
power factor is unity when the wattmeter readings are the same
b
15
When the frequency of the oscillator in a series RLC circuit is doubled:
Select one:
a. the capacitive reactance is doubled
b. the capacitive reactance is halved
c. the current amplitude is doubled
d. the impedance is doubled
b
16
An RLC circuit has a sinusoidal source of emf. The average rate at which
the source supplies energy is 5 nW. This must also be:
Select one:
a. The average rate at which energy is dissipated in the resistor.
b. The average rate at which energy is stored in the inductor.
c. Twice the average rate at which energy is stored in the capacitor.
d. The average rate at which energy is stored in the capacitor.
a
17
In an SCR, anode current flows over a narrow region near the gate during
______.
Select one:
a. more than μsec
b. rise time tr and spread time tp
c. about 10 µsec
d. delay time d
c
18
In a UJT, intrinsic standoff ratio, η, is typically:
Select one:
a. 0.2
b. 0.99
c. 0.4
d. 0.7
d
19
For a relay, the holding current is defined as:
Select one:
a. the maximum current the relay contacts can handle.
b. the minimum amount of relay coil current required to keep a relay
energized.
c. the maximum current required to operate relay.
d. the minimum amount of relay coil current required to energize a
relay.
b
20
If the secondary current in a step-down transformer increases, the primary
current will ____.
Select one:
a. drop a little
b. decrease
c. increase
d. not change
c
21
What is the purpose of a coupling capacitor?
Select one:
a. It decreases the resonant frequency of the circuit.
b. It blocks direct current and passes alternating current.
c. It blocks alternating current and passes direct current.
d. It increases the resonant frequency of the circuit.
b
22
A series connected C −R circuit is suddenly connected to a d.c. source of V
volts. Which of the statements is false?
Select one:
a. The initial voltage drop across the resistor is IR, where I is the steadystate current
b. The initial capacitor voltage is zero
c. The capacitor voltage is equal to the voltage drop across the resistor
d. The voltage drop across the resistor decays exponentially
c
23
Using the polar coordinate system, what visual representation would you
get of a voltage in a sinewave circuit?
Select one:
a. To graphically represent the AC and DC component.
b. To display the data on an XY chart.
c. The plot shows the magnitude and phase angle.
d. To show the reactance which is present.
c
24
What determines the visible color radiated by an LED junction?
Select one:
a. The amount of voltage across the device.
b. The materials used to construct the device.
c. The amount of current through the device.
d. The color of a lens in an eyepiece.
b
25
What is the voltage range considered to be a valid logic high input in a TTL
device operating at 5.0 volts?
Select one:
a. 1.5 to 3.0 volts.
b. 1.0 to 1.5 volts.
c. 5.2 to 34.8 volts
d. 2.0 to 5.5 volts
d
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100問 • 1年前問題一覧
1
Which of the following types of solder is best for radio and electronic use?
Select one:
a. Silver solder
b. Rosin-core solder
c. Aluminum solder
d. Acid-core solder
b
2
A series connected C −R circuit is suddenly connected to a d.c. source of V
volts. Which of the statements is false?
Select one:
a. The initial current flowing is given by V/R
b. The current grows exponentially
c. The final value of the current is zero
d. The time constant of the circuit is given by RC
b
3
Why is a pull-up resistor needed when connecting TTL logic to CMOS logic?
Select one:
a. To decrease the output LOW voltage
b. To increase the output HIGH voltage
c. To decrease the output HIGH voltage
d. To increase the output LOW voltage
b
4
A nickel-cadmium cell has an operating voltage of about ____ volts.
Select one:
a. 1.25
b. 1.5
c. 2.1
d. 1.4
a
5
According to Gauss' law for magnetism, magnetic field lines:
Select one:
a. start at south poles and end at north poles b. form closed loops
c. start at both north and south poles and end at infinity
d. start at north poles and end at south poles
b
6
Which of the following instruments would be best for checking a TTL logic
circuit?
Select one:
a. Continuity tester
b. DMM
c. Logic probe
d. VOM
c
7
What is an L-network?
Select one:
a. A network consisting of an inductor and a capacitor.
b. A "lossy" network.
c. A low power Wi-Fi RF network connection. d. A network formed by joining two low pass filters.
a
8
When examining the frequency response curve of an RC low-pass filer, it
can be seen that the rate of roll-off well above the cutoff frequency is
_______.
Select one:
a. 20 dB/decade
b. 6 dB/octave
c. Both 6 dB/octave and 20 dB/decade
d. 6 dB/decade
c
9
Iron, rather than copper, is used in the core of transformers because iron:
Select one:
a. Has a greater resistivity.
b. Can withstand a higher temperature.
c. Makes a good permanent magnet.
d. Has a very high permeability.
d
10
When a pulsating dc voltage is applied as an input to the primary of a
transformer, the output from the secondary contains:
Select one:
a. a stepped up or down version of pulsating dc voltage.
b. only the steady dc component of the input signal
c. only the ac component of the input signal.
d. None of the choices.
c
11
In normal operation, a p-n-p collector connected in common-base
configuration has:
Select one:
a. the collector at a lower potential than the emitter
b. the base at a higher potential than the emitter
c. the emitter at a lower potential than the base
d. the collector at a higher potential than the emitte
a
12
In normal operation, the junctions of an n-p-n transistor are:
Select one:
a. base-collector forward biased and base emitter reverse biased
b. base emitter forward biased and base collector reverse biased
c. both reverse biased
d. both forward biased
b
13
What waveform would appear on the voltage outputs at the collectors of
an astable multivibrator, common-emitter stage?
Select one:
a. Sawtooth wave.
b. Half-wave pulses.
c. Sine wave.
d. Square wave.
d
14
Which of the following statements is false?
Select one:
a. The national standard phase sequence for a three-phase supply is
R, Y, B.
b. For the same power, loads connected in delta have a higher line
voltage and a smaller line current than loads connected in star.
c. AC may be distributed using a single-phase system with two wires, a
three-phase system with three wires or a three-phase system with four
wires.
d. When using the two-wattmeter method of power measurement the
power factor is unity when the wattmeter readings are the same
b
15
When the frequency of the oscillator in a series RLC circuit is doubled:
Select one:
a. the capacitive reactance is doubled
b. the capacitive reactance is halved
c. the current amplitude is doubled
d. the impedance is doubled
b
16
An RLC circuit has a sinusoidal source of emf. The average rate at which
the source supplies energy is 5 nW. This must also be:
Select one:
a. The average rate at which energy is dissipated in the resistor.
b. The average rate at which energy is stored in the inductor.
c. Twice the average rate at which energy is stored in the capacitor.
d. The average rate at which energy is stored in the capacitor.
a
17
In an SCR, anode current flows over a narrow region near the gate during
______.
Select one:
a. more than μsec
b. rise time tr and spread time tp
c. about 10 µsec
d. delay time d
c
18
In a UJT, intrinsic standoff ratio, η, is typically:
Select one:
a. 0.2
b. 0.99
c. 0.4
d. 0.7
d
19
For a relay, the holding current is defined as:
Select one:
a. the maximum current the relay contacts can handle.
b. the minimum amount of relay coil current required to keep a relay
energized.
c. the maximum current required to operate relay.
d. the minimum amount of relay coil current required to energize a
relay.
b
20
If the secondary current in a step-down transformer increases, the primary
current will ____.
Select one:
a. drop a little
b. decrease
c. increase
d. not change
c
21
What is the purpose of a coupling capacitor?
Select one:
a. It decreases the resonant frequency of the circuit.
b. It blocks direct current and passes alternating current.
c. It blocks alternating current and passes direct current.
d. It increases the resonant frequency of the circuit.
b
22
A series connected C −R circuit is suddenly connected to a d.c. source of V
volts. Which of the statements is false?
Select one:
a. The initial voltage drop across the resistor is IR, where I is the steadystate current
b. The initial capacitor voltage is zero
c. The capacitor voltage is equal to the voltage drop across the resistor
d. The voltage drop across the resistor decays exponentially
c
23
Using the polar coordinate system, what visual representation would you
get of a voltage in a sinewave circuit?
Select one:
a. To graphically represent the AC and DC component.
b. To display the data on an XY chart.
c. The plot shows the magnitude and phase angle.
d. To show the reactance which is present.
c
24
What determines the visible color radiated by an LED junction?
Select one:
a. The amount of voltage across the device.
b. The materials used to construct the device.
c. The amount of current through the device.
d. The color of a lens in an eyepiece.
b
25
What is the voltage range considered to be a valid logic high input in a TTL
device operating at 5.0 volts?
Select one:
a. 1.5 to 3.0 volts.
b. 1.0 to 1.5 volts.
c. 5.2 to 34.8 volts
d. 2.0 to 5.5 volts
d