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Subelement B-005

B-005

Section B-005-013

Section B-005-013

How is a voltmeter usually connected to a circuit under test?

  • In series with the circuit
  • In phase with the circuit
  • Correct Answer
    In parallel with the circuit
  • In quadrature with the circuit

Key word: VOLTMETER. An instrument to measure voltage. The voltmeter is always connected in parallel to measure a difference of potential between two points, across a component, etc. The voltmeter must have high resistance not to affect the circuit.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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How is an ammeter usually connected to a circuit under test?

  • Correct Answer
    In series with the circuit
  • In parallel with the circuit
  • In phase with the circuit
  • In quadrature with the circuit

Key word: AMMETER. Ammeter comes from the words ampere + meter, it is used to measure current. Current flows THROUGH a circuit. The circuit must be 'broken' and the ammeter inserted in series with the circuit to measure current. Ammeters have very low resistance and, thus, have little effect once inserted in the circuit.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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What does a multimeter measure?

  • SWR and power
  • Correct Answer
    Voltage, current and resistance
  • Resistance, capacitance and inductance
  • Resistance and reactance

Common multimeters can measure the three basic electrical units: voltage (E), current (I) and resistance (R).

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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What is the correct instrument to measure the final power amplifier current?

  • A voltmeter
  • An ohmmeter
  • Correct Answer
    An ammeter
  • A wattmeter

Key word: CURRENT. Ammeter comes from the words ampere + meter, it is used to measure current.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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When measuring the voltage across a circuit component, what does the voltmeter appear to be in the circuit?

  • A perfect conductor
  • A low value resistance
  • Correct Answer
    A high value resistance
  • An open circuit

Key word: VOLTAGE. The voltmeter must have high resistance not to affect the circuit.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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When measuring current drawn from a DC power supply, what does the ammeter placed in the circuit appear as?

  • A perfect conductor
  • An additional load
  • Correct Answer
    A low value resistance
  • A high value resistance

This is a bit of a catch. A PERFECT conductor would exhibit ZERO resistance. An ammeter actually has very low resistance. [ For example, a 10 A ammeter can have a resistance of 0.005 ohms, a 1 A ammeter can have 0.05 ohms and a 500 mA ammeter can introduce 0.2 ohms of resistance in the circuit. ]

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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What instrument can provide a direct measurement of power at the output of a transmitter?

  • Ammeter
  • Field-strength meter
  • Correct Answer
    RF wattmeter
  • Wavemeter

Power is expressed in watts. The transmitter produces an electrical signal called "radiofrequency" (RF).

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

Potential difference is measured by means of:

  • an ohmmeter
  • a wattmeter
  • an ammeter
  • Correct Answer
    a voltmeter

The voltmeter is always connected in parallel to measure a difference of potential between two points, across a component, etc. The voltmeter must have high resistance not to affect the circuit.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

What instrument is used to measure electrical current?

  • Wattmeter
  • Wavemeter
  • Voltmeter
  • Correct Answer
    Ammeter

Ammeter comes from the words ampere + meter, it is used to measure current. Current flows THROUGH a circuit. The circuit must be 'broken' and the ammeter inserted in series with the circuit to measure current. Ammeters have very low resistance and, thus, have little effect once inserted in the circuit.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

What term describes the ability of an instrument to display values that are true to reality?

  • Stability
  • Correct Answer
    Accuracy
  • Resolution
  • Precision

Accuracy = agreement between measured value and true value. Precision = agreement between measured values on repeated measurements. Resolution = smallest change that can be measured. Stability = consistency in measurements over time.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

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