Correct option is B
CRO full form is Cathode Ray Oscilloscope, is a very fast X-Y plotter that can display an input signal versus time or another signal.
An electrical test device called a cathode ray oscilloscope is used to produce waveforms in response to several input signals.
The CRO is used to measure the voltage, current, frequency, inductance, admittance, resistance, and power factor.
This device is used to monitor the signal properties as well as characteristics and also controls the analog signals.
It was originally known as an oscillograph.
In a Cathode Ray Oscilloscope (CRO), the electron beam is directed and manipulated using the horizontal and vertical deflecting plates or coils.
These deflecting systems apply electric or magnetic fields to the electron beam, causing it to move in the desired direction across the phosphorescent screen. This allows the CRO to display waveforms and other signals by controlling the path of the electron beam.
The focusing and accelerating anodes help in forming and accelerating the beam, but they do not control its path once it has been formed.
The cathode ray is a beam of electrons which are emitted by the heated cathode (negative electrode) and accelerated toward the fluorescent screen.
The assembly of the cathode, intensity grid, focus grid, and accelerating anode (positive electrode) is called an electron gun.
o Its purpose is to generate the electron beam and control its intensity and focus.
Between the electron gun and the fluorescent screen are two pair of metal plates:
o one oriented to provide horizontal deflection of the beam and one pair oriented to give vertical deflection to the beam.
These plates are thus referred to as the horizontal and vertical deflection plates.
The combination of these two deflections allows the beam to reach any portion of the fluorescent screen.
Wherever the electron beam hits the screen, the phosphor is excited and light is emitted from that point.
This conversion of electron energy into light allows us to write with points or lines of light on an otherwise darkened screen.
In the most common use of the oscilloscope the signal to be studied is first amplified and then applied to the vertical (deflection) plates
o To deflect the beam vertically and at the same time a voltage that increases linearly with time is applied to the horizontal (deflection) plates thus causing the beam to be deflected horizontally at a uniform (constant> rate).
The signal applied to the vertical plates is thus displayed on the screen as a function of time.
The horizontal axis serves as a uniform time scale.
