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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 #245Basic Electricity and Electronics

Why should core saturation of a conventional impedance matching transformer be avoided?

  1. Harmonics and distortion could result ✓ Correct answer
  2. Magnetic flux would increase with frequency
  3. RF susceptance would increase
  4. Temporary changes of the core permeability could result

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Question #246Basic Electricity and Electronics

What is one reason to use an impedance matching transformer?

  1. To reduce power dissipation in the transmitter
  2. To maximize the transfer of power ✓ Correct answer
  3. To minimize SWR at the antenna
  4. To minimize SWR in the transmission line

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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 #248Basic Electricity and Electronics

Which of the following describes one method of impedance matching between two AC circuits?

  1. Insert an LC network between the two circuits ✓ Correct answer
  2. Reduce the power output of the first circuit
  3. Increase the power output of the first circuit
  4. Insert a circulator between the two circuits

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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 #250Basic Electricity and Electronics

How does the total current relate to the individual currents in each branch of a parallel circuit?

  1. It equals the average of each branch current
  2. It decreases as more parallel branches are added to the circuit
  3. It equals the sum of the currents through each branch (Kirchhoff’s Current Law) ✓ Correct answer
  4. It is the sum of the reciprocal of each individual voltage drop

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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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Question #252Radio Theory and Communication Principles

Frequency is

  1. cycles per second ✓ Correct answer
  2. Kilo cycles per second
  3. Cycles per minute
  4. cycles per hour

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Question #253Basic Electricity and Electronics

Resonant frequency in a tuned circuit is equal to

  1. 1/2piLC
  2. 1/2pi√LC ✓ Correct answer
  3. 2pi√LC
  4. 2pi√L+C

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Question #254Basic Electricity and Electronics

Power dissipated in a 400 Ohm resistor at 1 Amp is

  1. 40 Watts
  2. 400 KW
  3. 4 Watts
  4. 400 Watts ✓ Correct answer

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Question #255Basic Electricity and Electronics

Zener diode is used for

  1. Rectification
  2. Voltage regulation ✓ Correct answer
  3. Current regulation
  4. Switching

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Question #256Basic Electricity and Electronics

Plate current in a diode flows only when the plate is

  1. Negative with respect to cathode
  2. positive with respect to cathode
  3. when plate is at a lower voltage than cathode
  4. both at same potential ✓ Correct answer

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Question #257Basic Electricity and Electronics

3 resistors of 2,3 & 4 ohms are connected in series. The voltage across the circuit is 9 V , the current drawn by 3 ohms resistor is

  1. 1.5 Amps
  2. 27 Amps
  3. 1 Amp ✓ Correct answer
  4. 3 Amps

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Question #258Radio Theory and Communication Principles

A superhetrodyne receiver is tuned to 555 KHz and its local oscillator at 1010 KHz . The image frequency will be

  1. 1565 KHz ✓ Correct answer
  2. 455 KHz
  3. 1465 KHz
  4. none of these

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Question #259Radio Theory and Communication Principles

3 to 30 MHz band is known as

  1. MF
  2. LF
  3. VHF
  4. HF ✓ Correct answer

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Question #260Antennas and Radio Wave Propagation

The wavelength of a broadcast station at 1000 KHz is

  1. 30 Meters
  2. 300 Meters ✓ Correct answer
  3. 0.3 Meteors
  4. none of these

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