Mell How the bright spot is formed on the screen of CRO?
The fluorescent screen The screen is coated with a fluorescent salt, for example, zinc sulphide. When the electrons hit the screen, it will cause the salt to produce a flash of light and hence a bright spot on the screen.
What is luminous spot in case of CRO?
A cathode ray oscilloscope is a very fast X-Y plotter that can display an input signal versus time or another signal. Cathode ray oscilloscopes use luminous spots which are produced by striking the beam of electrons and this luminous spot moves in response variation in the input quantity.
What type of material produces the light on the screen of CRT when electrons strike?
Phosphors
Phosphors. The phosphors in a CRT’s screen are the materials that directly produce the photons generated by the CRT. These phosphors are struck by incoming electrons from the electron gun, absorb energy, and then re-emit some or all of that energy in the form of light (this process is called phosphorescence).
Why should a bright spot not be left on the display of the oscilloscope?
The INTENSITY control adjusts the brightness of the trace. A bright spot should never be left on the display because it will burn a spot on the face of the cathode ray tube (CRT). This burned spot results in permanent damage to the CRT.
What’s inside a cathode ray tube?
A cathode-ray tube (CRT) is a vacuum tube containing one or more electron guns, the beams of which are manipulated to display images on a phosphorescent screen. The images may represent electrical waveforms (oscilloscope), pictures (television set, computer monitor), radar targets, or other phenomena.
What is the application of oscilloscope?
Oscilloscopes can be used in wide variety of applications such as automotive test, protocol test, EMI precompliance analysis, signal analysis, conformance test, power measurements and many more. In most cases the oscilloscope has to be equiped with suitable options and/or probes.
What is the material used for screen of CRO?
The screen is coated with some fluorescent materials such as zinc orthosilicate, zinc oxide etc and is the inside face of the tube. When high velocity electron beam strikes the screen, a spot of light appears at the point of impact. The colour of the spot depends upon the nature of fluorescent material.
Where is the bright spot on a cathode ray oscilloscope?
No deflection occurs and the bright spot is at the centre. When a positive voltage or potential difference is applied to the Y-plates, the electrons in the beam will experience a force acting upwards causing the electron beam to deflect upwards. The bright spot moves to the top of the screen.
How does a cathode ray oscilloscope ( Cro ) work?
As we can see from the above figure above, a CRO employs a cathode ray tube ( CRT) ,which acts as the heart of the oscilloscope. In an oscilloscope, the CRT generates the electron beam which are accelerated to a high velocity and brought to focus on a fluorescent screen. This screen produces a visible spot where the electron beam strikes it.
How does electron beam move in cathode ray oscilloscope?
On application of proper potential to these plates, the electron beam can be made to move right and left horizontally on the screen. The screen is coated with some fluorescent materials such as zinc orthosilicate, zinc oxide etc and is the inside face of the tube.
How is a trigger pulse generated in a cathode ray oscilloscope?
The trigger pulse is generated by the time base generator to provide synchronization of the signals obtained from the horizontal and vertical amplifier. The electron gun generates the beam of electrons; these electron beam consists of several electrons moving towards phosphor screen.