This Portion of Electrical andElectronic Measurements and Measuring instruments contains Cathode Ray Oscilloscope (CRO) MCQs (Multiple Choice Questions and Answers) / Objective Type Questions and Answers.

This Section covers below lists of topics.

  1. Cathode Ray Tube (CRT)
  2. Electron Gun
  3. Oscilloscope Amplifiers
  4. Vertical input and sweep Generator Signal Synchronization
  5. Attenuators
  6. Basic CRO Circuits
  7. Observation of Waveforms on CRO
  8. Measurement of voltage and Currents
  9. Measurement of Phase and Frequency
  10. Multi-input Oscilloscopes
  11. Analog Storage Oscilloscopes
  12. Sampling Oscilloscopes
  13. Digital Storage Oscilloscopes
  14. Comparison between Analog and Digital Storage Oscilloscopes
  15. Accessories of cathode Ray Oscilloscopes

PRACTICE IT NOW TO SHARPEN YOUR CONCEPT AND KNOWLEDGE

1. The source of emission of electron in a CRT is :

  • PN Junction diode
  • A barium and strontium oxide coated cathode
  • Accelerating anodes
  • Post accelerating anodes.

2. In a CRT the focusing anode is located

  • Between pre-accelerating and accelerating anodes
  • After accelerating anodes
  • Before pre-accelerating anode
  • None of the above.

3. The deflection of an electron beam on a CTR screen is 10 mm. Suppose the pre-accelerating anode voltage is halved and the potential between deflecting plates is doubled, the deflection of the electron beam will be :

  • 80 mm
  • 40 mm
  • 20 mm
  • 10 mm

4. If the distance of screen from a CRT to centre of deflection plates is 15 cm, the length of deflection plates is 2 cm, the distance between plates is 1 cm and accelerating voltage is 500 V. the deflection sensitivity is :

  • 33.2 V/cm
  • 0.03 cm/V
  • 60.4 V/cm
  • 0.015 cm/V.

5. Post acceleration is needed in a CRO if the frequency of the signal is :

  • Less than 1MHz
  • More than 1MHz
  • More than 10MHz
  • More than 10Hz.

6. P1 phosphor material is used for display in CRTs for:

  • Photographic applications
  • General purpose applications
  • Television applications
  • All the above.

7. An aquadag is used in a CRO to collect :

  • Primary electrons
  • Secondary emission electrons
  • Both primary and secondary emission electrons
  • None of the above.

8. A thin aluminium film is usually deposited on the non viewing side of the phosphor because,

  • It act as a heat sink and prevents phosphor burn
  • The light scatter from the phosphor is reduced
  • It does not allow the screen to be negatively charged
  • All the above.

9. During the retrace time, the electrons forming the horizontal beam

  • Move from Left to right on the screen
  • Move from right to left on the screen
  • Move from bottom to top of screen
  • Move from top to bottom of screen

10. The bandwidth of a CRO is from  0 – 20 MHz. the fastest rise time a sine wave can have to be accurately reproduced by the instrument is

  • 35 ns
  • 35 µs
  • 17.5 ns
  • 0.175 µs.

11. The horizontal amplifier should be designed for

  • High frequency signals with a fast rise time
  • High amplitude signals with a slow rise time
  • High amplitude signals with high rise time
  • Low amplitude signals with a fast rise time

12. A vertical amplifier for a CRO can be designed for:

  • Only a high gain
  • Only a broad bandwidth
  • A constant gain times bandwidth product
  • All the above.

13. In an oscilloscope, when the unknown the unknown signals applied to the vertical plates is being synchronized with the sweep signal applied to horizontal plates, the pattern seen on the CRO screen moves towards the right. It means that,

  • The frequency of the signal is lower than that of the sweep signal
  • The frequency of the signal is greater than that of the sweep signal
  • The frequency of the signal is equal to the frequency of the sweep signal
  • None of the above.

14. An oscilloscope has an input capacitance of 50 pF and a resistance of 2 MΩ and the voltage divider ratio of 10. The parameter of high impedance probe are

  • C1 = 5.55pF, R1 = 18 MΩ
  • C1 = 3.33pF, R1 = 9 MΩ
  • C1 = 11.1pF, R1 = 18 MΩ
  • C1 = 5.55pF, R1 = 9 MΩ

15. In a digital storage oscilloscope, the input signals are

  • Directly applied to the oscilloscope
  • Multiplexed, converted to digital form and stored and applied to oscilloscope
  • Multiplexed, converted to digital form stored, converted to analog form and applied to oscilloscope
  • Applied to amplifier, stored as analog signals, multiplexed, converted to digital form, converted to analog form, and applied to CRO through an amplifier.

16. The time base signal in a CRO is

  • a sinusoidal signal
  • a sawtooth signal
  • a square wave signal
  • a triangular wave signal

17. In CRT aquadag carries

  • secondary emission electrons
  • sweep voltage
  • aqueous solution of graphite
  • none of these

18. In a CRO, the sawtooth voltage is applied at the

  • cathode
  • accelerating anode
  • vertical deflecting plates
  • horizontal deflecting plates

19. The purpose of the synchronising control in a CRO is to

  • adjust the amplitude of display
  • control the intensity of the spot
  • focus the spot on the screen
  • lock the display of signal

20. Retrace period for an ideal sawtooth waveform is

  • 0 second
  • equal to tracing period
  • infinite
  • none of these

21. In a CRT, the highest positive potential is given to

  • cathode
  • focusing electrodes
  • vertical deflecting plates
  • post-deflection acceleration anode

22. The X and Y inputs of a CRO are respectively V sin ωt and − V sin ωt. The resulting Lissajous pattern will be

  • a straight line
  • a circle
  • the shape of 8
  • an ellipse

23. The patterns used to measure phase and frequency with a cathode ray oscilloscope are called

  • Faraday’s pattern
  • Ohm’s patterns
  • Lissajous pattern
  • Phillips pattern

24. The voltage 10 cos ωt and V cos (ωt + α) are applied to the X and Y plates of a CRO. The Lissajous figure observed on the screen is a straight line of 60° to the positive axis. Then

  • V = 10, α = 60°
  • V = 10, α = 0°
  • V = 10 , α = 60°
  • V = 10 , α = 0°

25. Sampling oscilloscopes are specially designed to measure

  • very high frequency
  • very low frequency
  • microwave frequency
  • none of these

26. Which of the following statements is not correct for a storage-type oscilloscope?

  • Secondary emission electrons etch a positively charged pattern
  • The flood guns used for display, emit high velocity electrons
  • The flood guns are placed between the deflection plates and storage target.
  • The storage target is a conductive mesh covered with magnesium fluoride.

27. In a digital oscilloscope, the A/D converters are usually

  • ramp type
  • flash type
  • integrating type
  • successive approximate type

28. A double beam oscilloscope has

  • two screens
  • two electron guns
  • two different phosphor coatings
  • one waveform divided into two parts

29. Two equal voltages of same frequency applied to the X and Y plates of a CRO, produce a circle on the screen. The phase difference between the two voltages is

  • 150°
  • 90°
  • 60°
  • 30°

30. The Lissajous pattern on a CRO screen is shown in the given figure: The frequency ratio of the vertical signal to the horizontal one is

  • 3 : 2
  • 2 : 3
  • 5 : 1
  • 1 : 5

 

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