Ect001
Priority Level: High (ECE & ECT)
Questions and Answers
- 1.
Which of the following measurements are commonly made using a multimeter?
- A.
SWR and RF power
- B.
Signal strength and noise
- C.
Impedance and reactance
- D.
Voltage and resistance
Correct Answer
D. Voltage and resistanceExplanation
A multimeter is a versatile tool used for measuring electrical quantities. It is commonly used to measure voltage and resistance in various electrical circuits. Voltage refers to the electric potential difference between two points in a circuit, while resistance is the opposition to the flow of electric current. These measurements are fundamental in troubleshooting electrical problems, testing components, and ensuring the proper functioning of circuits. Therefore, voltage and resistance are commonly measured using a multimeter.Rate this question:
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- 2.
How many milliamperes is 1.5 amperes?
- A.
1500 milliamperes
- B.
15,000 milliamperes
- C.
150 milliamperes
- D.
15 milliamperes
Correct Answer
A. 1500 milliamperesExplanation
1.5 amperes is equal to 1500 milliamperes because there are 1000 milliamperes in one ampere. Therefore, to convert amperes to milliamperes, we multiply the given value by 1000.Rate this question:
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- 3.
Which is equal to 1,500,000 hertz?
- A.
1500 kHz
- B.
1500 MHz
- C.
15 GHz
- D.
150 kHz
Correct Answer
A. 1500 kHzExplanation
The correct answer is 1500 kHz. The unit "kHz" stands for kilohertz, which is equal to 1000 hertz. Therefore, 1500 kHz is equal to 1500 times 1000 hertz, which is 1,500,000 hertz.Rate this question:
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- 4.
Which is equal to one kilovolt?
- A.
One thousand volts
- B.
One million volts
- C.
One hundred volts
- D.
One one-thousandth of a volt
Correct Answer
A. One thousand voltsExplanation
One kilovolt is equal to one thousand volts.Rate this question:
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- 5.
Which is equal to one microvolt?
- A.
One one-millionth of a volt
- B.
One million volts
- C.
One thousand kilovolts
- D.
One one-thousandth of a volt
Correct Answer
A. One one-millionth of a voltExplanation
One microvolt is equal to one one-millionth of a volt. This means that it is a very small unit of measurement, as one volt is already a relatively small unit of electrical potential.Rate this question:
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- 6.
Which is equal to 500 milliwatts?
- A.
0.5 watts
- B.
0.02 watts
- C.
5 watts
- D.
50 watts
Correct Answer
A. 0.5 wattsExplanation
The correct answer is 0.5 watts because 500 milliwatts is equal to 0.5 watts. Since there are 1000 milliwatts in a watt, dividing 500 milliwatts by 1000 gives us 0.5 watts.Rate this question:
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- 7.
Which is equal to 3000 milliamperes?
- A.
3 amperes
- B.
3,000,000 amperes
- C.
0.3 amperes
- D.
0.003 amperes
Correct Answer
A. 3 amperesExplanation
The correct answer is 3 amperes because 1 ampere is equal to 1000 milliamperes. Therefore, 3 amperes is equal to 3000 milliamperes.Rate this question:
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- 8.
Which is equal to 3.525 MHz?
- A.
3525 kHz
- B.
3,525,000 kHz
- C.
35.25 kHz
- D.
0.003525 kHz
Correct Answer
A. 3525 kHzExplanation
The correct answer is 3525 kHz because kHz stands for kilohertz, which is a unit of frequency equal to 1000 hertz. Therefore, 3525 kHz is equal to 3525 multiplied by 1000 hertz, which is equivalent to 3.525 MHz (megahertz).Rate this question:
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- 9.
Which is equal to 1,000,000 picofarads?
- A.
1 microfarad
- B.
0.001 microfarads
- C.
1000 microfarads
- D.
1,000,000,000 microfarads
Correct Answer
A. 1 microfaradExplanation
The question asks for the equivalent value of 1,000,000 picofarads. Since 1 microfarad is equal to 1,000,000 picofarads, the answer is 1 microfarad.Rate this question:
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- 10.
Which decibel value most closely represents a power increase from 5 watts to 10 watts?
- A.
3 dB
- B.
2 dB
- C.
5 dB
- D.
10 dB
Correct Answer
A. 3 dBExplanation
dB = 10log(10/5) = 3Rate this question:
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- 11.
Which decibel value most closely represents a power decrease from 12 watts to 3 watts?
- A.
-6 dB
- B.
-9 dB
- C.
-3 dB
- D.
-1 dB
Correct Answer
A. -6 dBExplanation
dB = 10log(3/12) = -6Rate this question:
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- 12.
Which decibel value represents a power increase from 20 watts to 200 watts?
- A.
10 dB
- B.
12 dB
- C.
18 dB
- D.
28 dB
Correct Answer
A. 10 dBExplanation
dB = 10log(200/20) = 10Rate this question:
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- 13.
Which is equal to 28400 kHz?
- A.
28.400 MHz
- B.
284.00 MHz
- C.
2.800 MHz
- D.
28.400 kHz
Correct Answer
A. 28.400 MHzExplanation
The correct answer is 28.400 MHz because 1 MHz is equal to 1000 kHz. Therefore, to convert kHz to MHz, we divide the value by 1000. In this case, 28400 kHz divided by 1000 equals 28.400 MHz.Rate this question:
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- 14.
Which is equal to 2425 MHz?
- A.
2.425 GHz
- B.
0.002425 GHz
- C.
24.25 GHz
- D.
2425 GHz
Correct Answer
A. 2.425 GHzExplanation
The correct answer is 2.425 GHz. This is because 1 GHz is equal to 1000 MHz. Therefore, to convert from MHz to GHz, we divide the value in MHz by 1000. In this case, 2425 MHz divided by 1000 equals 2.425 GHz.Rate this question:
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- 15.
What is the abbreviation for megahertz?
- A.
MHz
- B.
MH
- C.
Mh
- D.
Mhz
Correct Answer
A. MHzExplanation
The correct answer is MHz, which stands for megahertz. Megahertz is a unit of measurement used to quantify the frequency of electromagnetic waves, particularly in relation to computer processing speeds and radio frequencies. The abbreviation "MHz" combines the lowercase "m" for "mega" and the uppercase "Hz" for "hertz."Rate this question:
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- 16.
What is the formula used to calculate electrical power (P) in a DC circuit?
- A.
P = I x E
- B.
P = E / I
- C.
P = E – I
- D.
P = I + E
Correct Answer
A. P = I x EExplanation
The formula used to calculate electrical power (P) in a DC circuit is P = I x E. This formula states that power is equal to the product of current (I) and voltage (E). In other words, power is determined by multiplying the current flowing through the circuit by the voltage across the circuit.Rate this question:
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- 17.
How much power is delivered by a voltage of 13.8 volts DC and a current of 10 amperes?
- A.
138 watts
- B.
0.7 watts
- C.
23.8 watts
- D.
3.8 watts
Correct Answer
A. 138 wattsExplanation
P = I x E = 10 x 13.8 = 138Rate this question:
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- 18.
How much power is delivered by a voltage of 12 volts DC and a current of 2.5 amperes?
- A.
30 watts
- B.
4.8 watts
- C.
14.5 watts
- D.
0.208 watts
Correct Answer
A. 30 wattsExplanation
P = I x E = 2.5 x 12 = 30Rate this question:
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- 19.
How much current is required to deliver 120 watts at a voltage of 12 volts DC?
- A.
10 amperes
- B.
0.1 amperes
- C.
12 amperes
- D.
132 amperes
Correct Answer
A. 10 amperesExplanation
I = P/E = 120/12 = 10Rate this question:
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- 20.
What is impedance?
- A.
The opposition to AC current flow.
- B.
The inverse of resistance.
- C.
The Q or Quality Factor of a component.
- D.
The power handling capability of a component.
Correct Answer
A. The opposition to AC current flow.Explanation
Impedance refers to the opposition that an electrical circuit presents to the flow of alternating current (AC). It is a combination of resistance, inductance, and capacitance in a circuit, and it is measured in ohms. Impedance determines how much current can flow through a circuit at a given voltage. Therefore, the statement "The opposition to AC current flow" accurately defines impedance.Rate this question:
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- 21.
What is the abbreviation for kilohertz?
- A.
KHz
- B.
KhZ
- C.
Khz
- D.
KHZ
Correct Answer
A. KHzExplanation
The correct abbreviation for kilohertz is kHz. The lowercase "k" represents the prefix kilo-, which means thousand, and the uppercase "Hz" stands for hertz, the unit of frequency. Therefore, kHz is the appropriate abbreviation for kilohertz.Rate this question:
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- 22.
What formula is used to calculate current in a circuit?
- A.
I = E / R
- B.
I = E x R
- C.
I = E + R
- D.
I = E - R
Correct Answer
A. I = E / RExplanation
The correct formula to calculate current in a circuit is I = E / R. This formula represents Ohm's Law, where I represents the current, E represents the voltage or electromotive force, and R represents the resistance. According to Ohm's Law, the current flowing through a circuit is equal to the voltage divided by the resistance.Rate this question:
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- 23.
What formula is used to calculate voltage in a circuit?
- A.
E = I x R
- B.
E = I / R
- C.
E = I + R
- D.
E = I - R
Correct Answer
A. E = I x RExplanation
The correct formula to calculate voltage in a circuit is E = I x R, where E represents voltage, I represents current, and R represents resistance. This formula is derived from Ohm's Law, which states that voltage is equal to the product of current and resistance. Therefore, to find the voltage in a circuit, one must multiply the current flowing through the circuit by the resistance it encounters.Rate this question:
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- 24.
What formula is used to calculate resistance in a circuit?
- A.
R = E / I
- B.
R = E x I
- C.
R = E + I
- D.
R = E - I
Correct Answer
A. R = E / IExplanation
The formula used to calculate resistance in a circuit is R = E / I. This formula represents Ohm's Law, where R is the resistance, E is the voltage or electromotive force, and I is the current flowing through the circuit. By dividing the voltage by the current, we can determine the resistance in the circuit.Rate this question:
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- 25.
What is the resistance of a circuit in which a current of 3 amperes flows when connected to 90 volts?
- A.
30 ohms
- B.
3 ohms
- C.
93 ohms
- D.
270 ohms
Correct Answer
A. 30 ohmsExplanation
R = E/I = 90/3 = 30Rate this question:
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- 26.
What is the resistance of a circuit for which the applied voltage is 12 volts and the current flow is 1.5 amperes?
- A.
8 ohms
- B.
13.5 ohms
- C.
0.125 ohms
- D.
18 ohms
Correct Answer
A. 8 ohmsExplanation
R = E/I = 12/1.5 = 8Rate this question:
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- 27.
What is the resistance of a circuit that draws 4 amperes from a 12-volt source?
- A.
3 ohms
- B.
16 ohms
- C.
48 ohms
- D.
8 ohms
Correct Answer
A. 3 ohmsExplanation
R = E/I = 12/4 = 3Rate this question:
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- 28.
Which of the following battery chemistries is not rechargeable?
- A.
Carbon-zinc
- B.
Nickel-cadmium
- C.
Lead-acid
- D.
Lithium-ion
Correct Answer
A. Carbon-zincExplanation
Carbon-zinc batteries are not rechargeable because the chemical reactions that occur during discharge are not easily reversible. Once the reactants are consumed, the battery cannot be recharged by reversing the chemical reactions. In contrast, nickel-cadmium, lead-acid, and lithium-ion batteries are all rechargeable as the chemical reactions can be reversed by applying an external electrical current.Rate this question:
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- 29.
Which is true about forward voltage drop in a diode?
- A.
It is lower in some diode types than in others.
- B.
It is proportional to peak inverse voltage.
- C.
It indicates that the diode is defective.
- D.
It has no impact on the voltage delivered to the load.
Correct Answer
A. It is lower in some diode types than in others.Explanation
The forward voltage drop in a diode refers to the voltage required for the diode to start conducting current in the forward direction. Different types of diodes have different forward voltage drops due to variations in their materials and construction. Some diodes, such as Schottky diodes, have lower forward voltage drops compared to others like standard silicon diodes. Therefore, it is true that the forward voltage drop is lower in some diode types than in others.Rate this question:
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- 30.
What electronic component allows current to flow in only one direction?
- A.
Diode
- B.
Driven element
- C.
Fuse
- D.
Resistor
Correct Answer
A. DiodeExplanation
A diode is an electronic component that allows current to flow in only one direction. It acts as a one-way valve for electric current, allowing it to pass through in one direction while blocking it in the opposite direction. This property is achieved due to the presence of a PN junction within the diode. When the diode is forward-biased, it allows current to flow freely, but when it is reverse-biased, it blocks the current. This characteristic makes diodes essential in many electronic circuits, such as rectifiers, voltage regulators, and signal demodulators.Rate this question:
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- 31.
Which of these components can be used as an electronic switch?
- A.
Transistor
- B.
Potentiometer
- C.
Thermistor
- D.
Varistor
Correct Answer
A. TransistorExplanation
A transistor can be used as an electronic switch because it has three terminals: emitter, base, and collector. By applying a small current or voltage to the base terminal, the transistor can control the flow of a larger current between the emitter and collector terminals. This allows the transistor to act as a switch, turning the larger current on or off depending on the input to the base terminal. This property makes transistors widely used in electronic circuits for various applications, including as switches.Rate this question:
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- 32.
Which of the following components can consist of three regions of semiconductor material?
- A.
Transistor
- B.
Alternator
- C.
Triode
- D.
Pentagrid converter
Correct Answer
A. TransistorExplanation
A transistor is a component that can consist of three regions of semiconductor material. These regions are called the emitter, base, and collector. The transistor is a crucial device in electronics as it can amplify or switch electronic signals and is widely used in various applications such as amplifiers, oscillators, and digital logic circuits. The other options listed, including the alternator, triode, and pentagrid converter, do not typically consist of three regions of semiconductor material.Rate this question:
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- 33.
What type of transistor has a gate, drain, and source?
- A.
Field-effect
- B.
Varistor
- C.
Tesla-effect
- D.
Bipolar junction
Correct Answer
A. Field-effectExplanation
A field-effect transistor (FET) has a gate, drain, and source. In a FET, the flow of current is controlled by an electric field applied to the gate terminal. The gate terminal acts as a control electrode, allowing the FET to function as a voltage-controlled device. The drain terminal is where the current enters the transistor, while the source terminal is where the current exits. This type of transistor is commonly used in many electronic devices due to its high input impedance and low power consumption.Rate this question:
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- 34.
How is the cathode lead of a semiconductor diode often marked on the package?
- A.
With a stripe
- B.
With the word "cathode"
- C.
With the letter C
- D.
With the letter K
Correct Answer
A. With a stripeExplanation
The cathode lead of a semiconductor diode is often marked on the package with a stripe. This stripe serves as a visual indicator to easily identify the cathode lead, which is the negative terminal of the diode. By marking the cathode lead with a stripe, it helps in correctly connecting the diode in a circuit, ensuring that it is properly oriented and functioning as intended.Rate this question:
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- 35.
What causes a light-emitting diode (LED) to emit light?
- A.
Forward current
- B.
Reverse current
- C.
Capacitively-coupled RF signal
- D.
Inductively-coupled RF signal
Correct Answer
A. Forward currentExplanation
When a forward current is applied to a light-emitting diode (LED), it causes the diode to emit light. This is because the forward current flows through the diode's p-n junction, causing electrons and holes to recombine and release energy in the form of photons. This process is known as electroluminescence and is the fundamental principle behind the operation of LEDs.Rate this question:
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- 36.
What does the abbreviation FET stand for?
- A.
Field Effect Transistor
- B.
Free Electron Transmitter
- C.
Fast Electron Transistor
- D.
Frequency Emission Transmitter
Correct Answer
A. Field Effect TransistorExplanation
The abbreviation FET stands for Field Effect Transistor. This is a type of transistor that uses an electric field to control the flow of current. It is commonly used in electronic devices for amplification and switching purposes. The other options, Free Electron Transmitter, Fast Electron Transistor, and Frequency Emission Transmitter, are not correct and do not accurately represent the meaning of FET.Rate this question:
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- 37.
What are the names for the electrodes of a diode?
- A.
Anode and cathode
- B.
Plus and minus
- C.
Source and drain
- D.
Gate and base
Correct Answer
A. Anode and cathodeExplanation
The correct answer is anode and cathode. In a diode, the anode is the positive electrode and the cathode is the negative electrode. The anode is where the current enters the diode, while the cathode is where the current exits. These terms are commonly used in electronic devices to distinguish between the two terminals of a diode.Rate this question:
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- 38.
Which of the following can provide power gain?
- A.
Transistor
- B.
Transformer
- C.
Reactor
- D.
Resistor
Correct Answer
A. TransistorExplanation
A transistor can provide power gain because it is a three-layer semiconductor device that can amplify electrical signals or switch them on and off. By controlling the input current or voltage, the transistor can regulate the output power to be greater than the input power. This amplification property makes transistors widely used in various electronic devices such as amplifiers, radios, and computers.Rate this question:
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- 39.
What is the term that describes a device's ability to amplify a signal?
- A.
Gain
- B.
Forward resistance
- C.
Forward voltage drop
- D.
On resistance
Correct Answer
A. GainExplanation
Gain is the correct answer because it refers to a device's ability to amplify a signal. Gain measures the ratio of output signal amplitude to input signal amplitude, indicating how much the signal is amplified by the device. In other words, gain describes the increase in signal strength provided by the device, making it the appropriate term to describe a device's ability to amplify a signal.Rate this question:
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- 40.
What are the names of the electrodes of a bipolar junction transistor?
- A.
Emitter, base, collector
- B.
Signal, bias, power
- C.
Input, output, supply
- D.
Pole one, pole two, output
Correct Answer
A. Emitter, base, collectorExplanation
The names of the electrodes of a bipolar junction transistor are emitter, base, and collector. These electrodes play crucial roles in the operation of the transistor. The emitter is responsible for emitting majority charge carriers, the base controls the flow of these carriers, and the collector collects the carriers that pass through the base. This configuration allows the transistor to amplify and control electrical signals, making it an essential component in electronic devices.Rate this question:
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- 41.
What is the name of an electrical wiring diagram that uses standard component symbols?
- A.
Schematic
- B.
Flow chart
- C.
Connector pinout
- D.
Bill of materials
Correct Answer
A. SchematicExplanation
A schematic is the name of an electrical wiring diagram that uses standard component symbols. It is a visual representation of an electrical circuit, showing how the various components are connected and how electricity flows through the system. Schematics are commonly used in electrical engineering and electronics to design, analyze, and troubleshoot circuits. They provide a concise and standardized way to communicate circuit information, making it easier for engineers and technicians to understand and work with electrical systems.Rate this question:
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- 42.
Which of the following is accurately represented in electrical schematics?
- A.
Component connections
- B.
Wire lengths
- C.
Physical appearance of components
- D.
All these choices are correct.
Correct Answer
A. Component connectionsExplanation
Electrical schematics accurately represent component connections. Schematics are diagrams that show the interconnections between various electrical components, such as resistors, capacitors, and transistors. They provide a visual representation of how these components are connected to each other and to power sources. Schematics do not typically include information about wire lengths or the physical appearance of components, as these details are not essential for understanding the electrical connections. Therefore, the correct answer is that component connections are accurately represented in electrical schematics.Rate this question:
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- 43.
Which of the following devices or circuits changes an alternating current into a varying direct current signal?
- A.
Rectifier
- B.
Transformer
- C.
Amplifier
- D.
Reflector
Correct Answer
A. RectifierExplanation
A rectifier is a device that converts alternating current (AC) into direct current (DC) by allowing current to flow in one direction only. It uses diodes to block the negative portion of the AC waveform, resulting in a varying DC signal. Therefore, a rectifier is the correct device or circuit that changes an alternating current into a varying direct current signal.Rate this question:
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- 44.
What is a relay?
- A.
An electrically-controlled switch.
- B.
A current controlled amplifier.
- C.
An inverting amplifier.
- D.
A pass transistor.
Correct Answer
A. An electrically-controlled switch.Explanation
A relay is an electrically-controlled switch that uses an electromagnet to open or close a circuit. When an electric current is applied to the relay, it generates a magnetic field that attracts a metal armature, causing it to move and either make or break the circuit. This allows the relay to control the flow of electricity to other devices or components in a circuit. Relays are commonly used in various applications, such as in automotive systems, industrial machinery, and home automation, where they provide a reliable and efficient way to control power circuits.Rate this question:
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- 45.
Which of the following is a reason to use shielded wire?
- A.
To prevent coupling of unwanted signals to or from the wire.
- B.
To couple the wire to other signals.
- C.
To increase the current carrying capability of the wire.
- D.
To decrease the resistance of DC power connections.
Correct Answer
A. To prevent coupling of unwanted signals to or from the wire.Explanation
Shielded wire is used to prevent the coupling of unwanted signals to or from the wire. This means that the wire is protected from external electromagnetic interference, ensuring that the signals being transmitted through the wire are not distorted or corrupted. Shielded wire is commonly used in applications where signal integrity is critical, such as in audio and video cables, data transmission cables, and sensitive electronic circuits. By preventing the coupling of unwanted signals, shielded wire helps to maintain the quality and reliability of the transmitted signals.Rate this question:
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- 46.
Which of the following displays an electrical quantity as a numeric value?
- A.
Meter
- B.
Relay
- C.
Transistor
- D.
Potentiometer
Correct Answer
A. MeterExplanation
A meter is a device that is used to measure and display electrical quantities as numeric values. It is commonly used to measure parameters such as voltage, current, resistance, and power. Meters typically have a digital or analog display that shows the measured value in a numeric format, making it easy for users to read and interpret the electrical quantity being measured.Rate this question:
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- 47.
What type of circuit controls the amount of voltage from a power supply?
- A.
Regulator
- B.
Oscillator
- C.
Filter
- D.
Phase inverter
Correct Answer
A. RegulatorExplanation
A regulator is a type of circuit that controls the amount of voltage from a power supply. It ensures that the voltage output remains constant even when there are fluctuations in the input voltage or changes in the load. By regulating the voltage, a regulator protects the electronic components from damage and ensures their proper functioning. It is commonly used in power supplies for various electronic devices to provide a stable and reliable source of voltage.Rate this question:
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- 48.
What component changes 220 V AC power to a lower AC voltage for other uses?
- A.
Transformer
- B.
Variable capacitor
- C.
Transistor
- D.
Diode
Correct Answer
A. TransformerExplanation
A transformer is a device that is used to change the voltage of an alternating current (AC) power supply. It works on the principle of electromagnetic induction, where two coils of wire are wound around an iron core. The primary coil is connected to the 220 V AC power source, while the secondary coil is connected to the load. By varying the number of turns in each coil, the transformer can step up or step down the voltage. In this case, the transformer is used to lower the 220 V AC power to a lower AC voltage for other uses.Rate this question:
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- 49.
Which of the following is commonly used as a visual indicator?
- A.
LED
- B.
FET
- C.
Zener diode
- D.
Bipolar transistor
Correct Answer
A. LEDExplanation
LED stands for Light Emitting Diode, which is a semiconductor device that emits light when an electric current passes through it. LEDs are commonly used as visual indicators because they are small, energy-efficient, and can emit light in various colors. They are often used in electronic devices, such as smartphones, televisions, and indicators on appliances, to provide visual feedback or display information. LEDs are also used in automotive lighting, street lights, and signage due to their long lifespan and durability.Rate this question:
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- 50.
Which of the following is combined with an inductor to make a resonant circuit?
- A.
Capacitor
- B.
Potentiometer
- C.
Zener diode
- D.
Resistor
Correct Answer
A. CapacitorExplanation
A resonant circuit is a circuit that exhibits resonance at a specific frequency. In order to create a resonant circuit, an inductor needs to be combined with a capacitor. The inductor provides the inductance, while the capacitor provides the capacitance. Together, they create a circuit that can store and release energy at the resonant frequency, resulting in a strong response to that particular frequency. The other options, such as potentiometer, zener diode, and resistor, do not have the necessary properties to create a resonant circuit when combined with an inductor.Rate this question:
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