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194 matching questions

Question #202Radio Theory and Communication Principles

What is another way to specify the frequency of a radio signal that is oscillating at 1,500,000 Hertz?

  1. 1500 kHz ✓ Correct answer
  2. 1500 MHz
  3. 15 GHz
  4. 150 kHz

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Question #203Radio Theory and Communication Principles

How many volts are equal to one kilovolt?

  1. One one-thousandth of a volt
  2. one hundred volts
  3. one thousand volts ✓ Correct answer
  4. one million volts

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Question #204Radio Theory and Communication Principles

How many volts are equal to one microvolt?

  1. one one-millionth of a volt ✓ Correct answer
  2. one million volts
  3. one thousand kilovolts
  4. one one-thousandth of a volt
Explanation: One microvolt is 10⁻⁶ volt, or one-millionth of a volt.

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Question #218Radio Theory and Communication Principles

What type of component is a thermistor?

  1. A resistor that is resistant to changes in value with temperature variations
  2. A device having a controlled change in resistance with temperature variations ✓ Correct answer
  3. A special type of transistor for use at very cold temperatures
  4. A capacitor that changes value with temperature

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Question #227Radio Theory and Communication Principles

Which of the following describes the construction of a MOSFET?

  1. The gate is formed by a back-biased junction
  2. The gate is separated from the channel with a thin insulating layer ✓ Correct answer
  3. The source is separated from the drain by a thin insulating later
  4. The source is formed by depositing metal on silicon

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Question #228Radio Theory and Communication Principles

Which element of a triode vacuum tube is used to regulate the flow of electrons between cathode and plate?

  1. Control grid ✓ Correct answer
  2. Heater
  3. Screen Grid
  4. Suppressor grid

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Question #229Radio Theory and Communication Principles

Which of the following solid state devices is most like a vacuum tube in its general characteristics?

  1. A bipolar transistor
  2. An FET ✓ Correct answer
  3. A Tunnel diode
  4. A varistor

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Question #230Radio Theory and Communication Principles

What is the primary purpose of a screen grid in a vacuum tube?

  1. To reduce grid-to-plate capacitance ✓ Correct answer
  2. To increase efficiency
  3. To increase the high frequency response
  4. To decrease plate resistance

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Question #233Radio Theory and Communication Principles

When is it acceptable to recharge a carbon-zinc primary cell?

  1. As long as the voltage has not been allowed to drop below 1.0 volt
  2. When the cell is kept warm during the recharging period
  3. When a constant current charger is used
  4. Never ✓ Correct answer

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Question #234Radio Theory and Communication Principles

Which of the following is a rechargeable battery?

  1. Carbon-zinc
  2. Silver oxide
  3. Nickel Metal Hydride ✓ Correct answer
  4. Mercury

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Question #235Radio Theory and Communication Principles

What is impedance?

  1. The electric charge stored by a capacitor
  2. The inverse of resistance
  3. The opposition to the flow of current in an AC circuit ✓ Correct answer
  4. The force of repulsion between two similar electric fields

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Question #236Radio Theory and Communication Principles

What is reactance?

  1. Opposition to the flow of direct current caused by resistance
  2. Opposition to the flow of alternating current caused by capacitance or inductance ✓ Correct answer
  3. A property of ideal resistors in AC circuits
  4. A large spark produced at switch contacts when an inductor is de-energized

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Question #239Radio Theory and Communication Principles

How does a coil react to AC?

  1. As the frequency of the applied AC increases, the reactance decreases
  2. As the amplitude of the applied AC increases, the reactance increases
  3. As the amplitude of the applied AC increases, the reactance decreases
  4. As the frequency of the applied AC increases, the reactance increases ✓ Correct answer

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Question #241Radio Theory and Communication Principles

What happens when the impedance of an electrical load is equal to the internal impedance of the power source?

  1. The source delivers minimum power to the load
  2. The electrical load is shorted
  3. No current can flow through the circuit
  4. The source can deliver maximum power to the load ✓ Correct answer

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Question #242Radio Theory and Communication Principles

Why is impedance matching important?

  1. So the source can deliver maximum power to the load ✓ Correct answer
  2. So the load will draw minimum power from the source
  3. To ensure that there is less resistance than reactance in the circuit
  4. To ensure that the resistance and reactance in the circuit are equal

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Question #243Radio Theory and Communication Principles

What unit is used to measure reactance?

  1. Farad
  2. Ohm ✓ Correct answer
  3. Ampere
  4. Siemens

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Question #244Radio Theory and Communication Principles

What unit is used to measure impedance?

  1. Volt
  2. Ohm ✓ Correct answer
  3. Ampere
  4. Watt

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Question #247Radio Theory and Communication Principles

Which of the following devices can be used for impedance matching at radio frequencies?

  1. A transformer
  2. A Pi-network
  3. A length of transmission line
  4. All of these choices are correct ✓ Correct answer

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Question #249Radio Theory and Communication Principles

A two-times increase or decrease in power results in a change of how many dB?

  1. 2 dB
  2. 3 dB ✓ Correct answer
  3. 6 dB
  4. 12 dB

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Question #251Radio Theory and Communication Principles

Capacitance is measured in

  1. Amperes
  2. watt
  3. Farad ✓ Correct answer
  4. Coulombs

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