Gibilisco - Electron Tubes

20 Questions

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Electron Quizzes & Trivia

Questions and Answers
  • 1. 
    A major difference between a triode tube and an N-channel FET is the fact that
    • A. 

      Triodes work with lower signal voltages.

    • B. 

      Triodes are more compact.

    • C. 

      Triodes need higher power-supply voltages.

    • D. 

      Triodes don’t need filaments.

  • 2. 
    The control grid of a vacuum tube is the electrical counterpart of the
    • A. 

      Source of a MOSFET.

    • B. 

      Collector of a bipolar transistor.

    • C. 

      Anode of a diode.

    • D. 

      Gate of an FET.

  • 3. 
    In a tetrode tube, the charge carriers are
    • A. 

      Free electrons, which pass among the electrodes.

    • B. 

      Holes, which are conducted within the electrodes.

    • C. 

      Holes or electrons, depending on whether the device is P type or N type.

    • D. 

      Nuclei of whatever elemental gas happens to exist in the tube.

  • 4. 
    Which factor is most significant in limiting the maximum frequency at which a tube canoperate?
    • A. 

      The power-supply voltage

    • B. 

      The capacitance among the electrodes

    • C. 

      The physical size of the tube

    • D. 

      The current passing through the filament

  • 5. 
    In a tube with a directly heated cathode,
    • A. 

      The filament is separate from the cathode.

    • B. 

      The grid is connected to the filament.

    • C. 

      The filament serves as the cathode.

    • D. 

      There is no filament.

  • 6. 
    In a tube with a cold cathode,
    • A. 

      The filament is separate from the cathode.

    • B. 

      The grid is connected to the filament.

    • C. 

      The filament serves as the cathode.

    • D. 

      There is no filament.

  • 7. 
    A screen grid enhances tube operation by
    • A. 

      Increasing the gain, helping the circuit to oscillate more easily.

    • B. 

      Decreasing the plate voltage required to produce oscillation.

    • C. 

      Minimizing the risk that a tube amplifier will break into oscillation.

    • D. 

      Pulling excess electrons from the plate.

  • 8. 
    A tube with three grids is called a
    • A. 

      Triode.

    • B. 

      Tetrode.

    • C. 

      Pentode.

    • D. 

      Hexode.

  • 9. 
    A tube with four grids is called a
    • A. 

      Triode.

    • B. 

      Tetrode.

    • C. 

      Pentode.

    • D. 

      Hexode.

  • 10. 
    An advantage of a grounded-grid RF power amplifier over a grounded-cathode RF poweramplifier is the fact that the grounded-grid circuit
    • A. 

      Has excellent sensitivity.

    • B. 

      Exhibits high input impedance.

    • C. 

      Produces little or no noise in the input.

    • D. 

      Is more stable.

  • 11. 
    A heptode tube has
    • A. 

      One plate.

    • B. 

      Two plates.

    • C. 

      Three plates.

    • D. 

      Four plates.

  • 12. 
    The electron gun in a CRT is another name for its
    • A. 

      Cathode.

    • B. 

      Anode.

    • C. 

      Control grid.

    • D. 

      Screen grid.

  • 13. 
    The electron beam in an electrostatic CRT is bent by
    • A. 

      Magnetic fields produced by current-carrying coils.

    • B. 

      Electric fields produced by charged electrodes.

    • C. 

      A variable voltage on the screen grid.

    • D. 

      Visible light striking the electrodes.

  • 14. 
    A grounded-grid RF power amplifier
    • A. 

      Requires more driving power, for a given RF power output, than a grounded-cathode RF power amplifier.

    • B. 

      Requires less driving power, for a given RF power output, than a grounded-cathode RF power amplifier.

    • C. 

      Oscillates at a more stable frequency than a grounded-cathode RF power amplifier.

    • D. 

      Oscillates at a less stable frequency than a grounded-cathode RF power amplifier.

  • 15. 
    In a Klystron, the electron-beam density varies as a result of
    • A. 

      Amplitude modulation.

    • B. 

      Pulse modulation.

    • C. 

      Velocity modulation.

    • D. 

      Frequency modulation.

  • 16. 
    A vidicon camera tube is noted for its
    • A. 

      Poor signal-to-noise ratio.

    • B. 

      Large size and heavy weight.

    • C. 

      Slow response to image movement in dim light.

    • D. 

      Excellent selectivity and electrical ruggedness.

  • 17. 
    The plate in a tetrode tube is normally connected to
    • A. 

      A positive dc power-supply voltage.

    • B. 

      A negative dc power-supply voltage.

    • C. 

      Electrical ground.

    • D. 

      RF ground.

  • 18. 
    The screen grid in a tetrode tube is normally connected to
    • A. 

      A positive dc power-supply voltage.

    • B. 

      A negative dc power-supply voltage.

    • C. 

      Electrical ground.

    • D. 

      RF ground.

  • 19. 
    Which of the following is most suitable for measuring the intensity of dim light?
    • A. 

      A triode gas-filled tube

    • B. 

      A photomultiplier tube

    • C. 

      An electrostatic CRT

    • D. 

      An electromagnetic CRT

  • 20. 
    In a dissector tube, the aperture size is directly related to the
    • A. 

      Operating voltage.

    • B. 

      Signal-to-noise ratio.

    • C. 

      Response speed.

    • D. 

      Image resolution.