Basic Control:- The basic control in CRO consists of
On-off knob
Intensity or Brightness
Focus
Focus Control
Scale Illumination
Horizontal Section Consist of four parts
Position Knob
Timebase control
Sweep selector switch
Synchronization
The measure part of the vertical section is
Vertical Scale
Invert
Position
X10 knob
Vertical coupling Switch
Vertical Mode Control
2. ______ is used to shift the inputs in CRO.
Position Knob
X10 Knob
Alternate Knob
Any of the above
Answer.3. Alternate Knob
Explanation:
In a Cathode Ray Oscilloscope, the alternate knob is used to transition between the two different input signals.
Input A is displayed first, then input B is displayed, then input Aagainand soon by using the vertical position control, the two traces can be separated vertically, and thus, relations between the two signals can be studied.
3. What is the role of the intensity section in a CRO?
Decreases the light intensity
Controls light intensity
Increases the light intensity
Keeps the light intensity zero
Answer.2. Controls light intensity
Explanation:
Intensity or Brightness: The intensity section in a CRO controls the intensity or brightness of the light produced by the beam spot.
It actually controls the number of electrons per second that are bombarding the screen which determines the brightness of the spot.
In general, the spot should be no brighter than it needs to be since high-intensity spots shorten the life of the cathode ray tube.
Also allowing the bright spot to stand still for a long time at the same position on the screen, can burn off the phosphor on the tube and produce a dead spot on the screen at that point.
4. Position knob in a CRO indicates ________
Voltage position only
Time position only
Current position only
Any pattern’s position
Answer.4. Any pattern’s position
Explanation:
Position Knob: In a CRO the position knob is used for indicating the position of any pattern on the screen. The position knob is used to shift the display as a whole to left or right.
There are two knobs — one for controlling the horizontal position and another for controlling the vertical position. The spot can be moved to left or right i.e. horizontally with the help of a knob, which regulates the dc potential applied to the horizontal deflection plates, in addition to the usual sawtooth-wave.
5. What is the role of the focus section in a CRO?
Increases the focus
Decreases the focus
Controls sharpness
Maintains the focus zero
Answer.3. Controls sharpness
Explanation:
Focus: The focus section in a CRO controls the sharpness of the spot. A sharper spot is always preferred. The focusing of the spot is also obtained by varying the voltage applied to the focusing anodes of the cathode ray tube.
Focus Control: It is also known as Astigmatism. This is another focus control. With the help of focus control and astigmatism control, a very sharp spot can be obtained both in the center and also at the edges of the screen.
6. X10 in a CRO means ______
One-tenth
Control knob
10 times as normal
Attenuate the voltage by 10 times
Answer.2. Control knob
Explanation:
X10 in a CRO means Control knob.
X10 Knob: This control makes the gain of the vertical amplifier 10 times as great as normal, it changes the scale factor by a factor of 10. Thus if the X 10 switch turned ‘ON” and the scope is set to 0.05 V/cm, if the actual scale factor is 0.005 V/cm, if the actual scale factor is 0.005 V/ cm or 5 mV/em.
7. What is the role of astigmatism in a CRO?
Increases the intensity
Used for voltage stability
Diminishes the intensity
Focus control
Answer.4. Focus control
Explanation:
The role of astigmatism in a CRO is Focus control.
Focus Control: It is also known as Astigmatism. This is another focus control. With the help of focus control and astigmatism control, a very sharp spot can be obtained both in the center and also at the edges of the screen.
8. What is the role of an invert in a CRO?
Inverts the output
Inverts the input
Attenuates the input
Magnifies the input
Answer.2. Inverts the input
Explanation:
Invert in a CRO control inverts the input signal; That is, it multiplies it by-1. Then positive input voltages become negative and cause downward deflections.
9. What is the role of scale illumination in a CRO?
Measurement
Illumination
Sharpness
Stability
Answer.1. Measurement
Explanation:
The role of scale illumination in a CRO is used for measurement.
Most of the C.R.O have some sort of plastic screen in front of the cathode ray tube.
This screen has a grid engraved on it, giving it an appearance similar to that of graph paper. This is called graticule.
This scale facilitates the measurement of the oscilloscope.
The scale illumination control illuminates the scale and hence the lines on the scale can be seen very easily.
The electrons striking the screen are either repelled back or cause the secondary emission of electrons.
The secondary electron affects the display on the screen.
Hence to collect such electrons, a conductive coating is deposited inside the surface of CRT, except the screen.
10. The time base control in CRO is calibrated in terms of ______
Time per meter
Time per centimeter
Meter per second
Division per time
Answer.2. Time per centimeter
Explanation:
Time Base Control: The oscilloscope is usually used to observe the waveform of time-varying signals. Most of the horizontal section of the scope is devoted to generating a time base for such signals. The time base control is calibrated in terms of time per centimeter or time per division.
11. When the sweep selectors switch is in _____ position, the horizontal amplifier receives an input from the sawtooth sweep generator.
Vertical Position
Horizontal Position
Linear Position
Any of the above
Answer.3. Linear Position
Explanation:
Sweep Selector Switch: When the sweep selectors switch S, is in a linear position, the horizontal amplifier receives an input from the sawtooth sweep generator which is triggered by the synchronous amplifier.
12. The function of synchronization switch in CRO is _____
To obtain vertical pattern
To obtain horizontal pattern
To obtain stationary pattern
All of the above
Answer.3. To obtain stationary pattern
Explanation:
Synchronization: To obtain the stationary pattern on the screen, synchronization is used.
It is used to operate the time base generator such that the frequency of sawtooth voltage is an integral multiple of input signal frequency.
There are various signals which can be applied to the trigger circuit. The signals can be selected using a synchronous selector switch.
13. The choice of vertical coupling switch in CRO is _____
AC
DC
Ground
All of the above
Answer.4. All of the above
Explanation:
Vertical Coupling Switches: This switch controls the coupling to the vertical amplifier. The usual choice is AC, DC or ground. The meaning of these various positions are as follows:
(i) DC: The vertical amplifier had dc coupling throughout so that the deflection corresponds to both the ac and the dc components of the input.
(ii) AC: The vertical amplifier is ac coupled to the input. Thus the dc component of the input is blocked and only the ac components of the input signals deflect the beam vertically. This allows observing small ac signals or large dc background.
(iii) Ground: The input to the amplifier is grounded. There will be no vertical deflection. If no voltage is applied to horizontal plates, the spot will be at the position corresponding to the ground. It is useful for measuring voltage with respect to the ground.
14. The chop mode in CRO is used for
High frequency Only
Low Frequency Only
Both high and low frequency Only
None of the above
Answer.3. Both high and low frequency Only
Explanation:
Chop: In this mode first input A is displayed for a fraction of a microsecond, then input B for a fraction of microsecond, then input A again, and so on.
In this way, plots of both inputs can be drawn at the same time.
The chop mode is useful with low-frequency signals, while the alternate mode is useful for high-frequency signals.
15. The Z-axis control in CRO is used for
Increases the Brightness
Decreases the focus
Controls sharpness
Maintains the focus zero
Answer.1. Increases the Brightness
Explanation:
The Z-axis control in CRO is used for brightening the display.
The periodic positive pulse is applied to the grid and alternatively, a negative pulse is applied to the cathode, to brighten the beam during its sweep period.
This control is obtained by inserting a signal between the ground and the control grid or ground and the cathode.
