Rabobi Rayu na Kasa | CRO

Muhimmiya Rayi Oscilloscope Na Cathode?

An Oscilloscope Na Cathode Ray (CRO) shine karamin zanar da ake yi a makarantun ilimi don in tafi, cikakki da tattauna wasu manyan tsari na zangon kwai. An oscilloscope na cathode ray ya shahara da X-Y plotter mai kyau wanda ya iya tafi masu inganta a kan lokaci ko zama.

Oscilloscopes na cathode ray suna amfani da dabba-dabba daban-daban da suka samu a kan beam na electrons kuma wannan dabba ya ci gaba a kan yawan yadda ake bayyana masu inganta. A nan muna nufin a fuskantar mutum yadda ake amfani da beam na electrons kawai. Sabubban haka shine yadda abubuwa da beam na electrons ya ba ake amfani don tabbatar da yadda masu inganta suka ci gaba. Tsarin daidai na oscilloscope na cathode ray sun yi aiki a kan voltages.

Saboda haka, masu inganta da muna magana a nan shine voltage. Yanzu, da ake amfani da transducers, ana iya girma wasu manyan abubuwa kamar current, pressure, acceleration, kafin voltage, saboda haka ta ba mukan da tafi masu inganta a kan oscilloscope na cathode ray. Tana da ma a bincika cikakken tsarin oscilloscope na cathode ray.

Cikakken Tsarin Oscilloscope Na Cathode Ray

Babbar baki na oscilloscope na cathode ray shine cathode ray tube wanda ake kira babbar baki na oscilloscope na cathode ray.

Yana da kyau a bincika cikakken cathode ray tube don in fahimta cikakken oscilloscope na cathode ray. Bisa ga, cathode ray tube tana da lambar baki uku:

1. Electron gun

2. Deflection plate system

3. Fluorescent screen

4. Glass envelope

5. Base

Za a bukata duk 5 min daga baya zuwa DIY oscilloscope. Zan iya bayyana waɗannan 5 min tsohuwar:

Electron Gun:
Shi ne masu inganta, energized da focused beam na electrons. An taka da shekaru biyar baki, shine heater, cathode, grid, pre-accelerating anode, focusing anode da accelerating anode. Don in samun gyara electrons, an ruhu barium oxide (wanda ake sanya a kan cathode) a kan temperature mai yawa. Electrons bayan haka sun haɗa a kan hole mai yawa na control grid wanda ake gina a kan nickel. Kamar sunan ya nuna, control grid tana kontrola adadin electrons ko inda muna cewa gyaran electrons daga cathode. Bayan haɗa a kan control grid, electrons sun haɗa a kan pre-accelerating da accelerating anodes. Pre-accelerating da accelerating anodes suna haɗa a kan common positive potential na 1500 volts.

Bayan haka, abin da focusing anode ke yi shine focus beam na electrons da aka samu. Focusing anode tana haɗa a kan adjustable voltage na 500 volts. Yana da biyu na hukuma da za a iya focus electron beam, da aka rubuta a nan:

1. Electrostatic focusing.

2. Electromagnetic focusing.

A nan zan iya bayyana electrostatic focusing method da kuma.

Electrostatic Focusing
A neman cewa force na electron tana ba a kan - qE, inda q tana ba charge na electron (q = 1.6 × 10-19 C), E tana ba electric field intensity da negative sign tana nuna cewa direction na force tana ba a kan opposite direction to that of electric field. Bayan haka, za a amfani da wannan force don defect beam na electrons daga electron gun. Za a duba biyu na hukuma:

Case One
A nan muna da plates biyu A da B kamar yadda ake bayyana a kan figure.

Plate A tana haɗa a kan potential +E, sai dai plate B tana haɗa a kan potential –E. Direction na electric field tana ba a kan A plate to plate B at right angle to the surfaces of the plate. Equipotential surfaces suna ba a kan diagram, kamar yadda ake nuna perpendicular to the direction na electric field. Idan beam na electron ya haɗa a kan plate system, ita ce deflection a kan opposite direction na electric field. Deflection angle tana iya canza a kan changing the potential of the plates.

Case Second
A nan muna da concentric cylinders biyu da potential difference applied between them kamar yadda ake bayyana a kan figure.

Resultant direction na electric field da equipotential surfaces suna ba a kan figure. Equipotential surfaces suna ba a kan dotted lines kamar yadda ake nuna curved in shape. Bayan haka, muna da shawarar cewa deflection angle na electron beam idan ita haɗa a kan curved equipotential surface. Za a duba curved equipotential surface S kamar yadda ake bayyana a nan. Potential on the right side of the surface is +E, sai dai potential on the left side of the surface –E. Idan beam na electron ya haɗa a kan angle A to the normal, ita ce deflection by angle B after passing through the surface S kamar yadda ake bayyana a kan figure. Normal component na velocity na beam tana ci gaba saboda force tana ba a kan s direction normal to the surface. Meaning, tangential velocities tana bai same, so by equating the tangential components we have V1sin (A) = V2sin(B), where V1 tana ba initial velocity na electrons, V2 tana ba velocity after passing through the surface. Now we have relation as sin(A)/sin(B)=V2 / V1.
We can from the above equation see that there is bending of the electron beam after passing through the equipotential surface. Therefore this system is also called focusing system.

Electrostatic Deflection
In order to find out the expression for the deflection, let us consider a system as shown below:


In the above system we have two plates A and B which are at potential +E and 0 respectively. These plates are also called deflection plates. The field produced by these plates is in the direction of positive y axis and there is no force along the x-axis. After deflection plates we have screen through which we can measure net deflection of the electron beam. Now let us consider a beam of electron coming along the x-axis as shown in the figure. The beam deflects by angle A, due presence of electric field and deflection is in the positive direction of y axis as shown in the figure. Now let us derive an expression for deflection of this beam. By the conservation of energy, we have loss in potential energy when the electron moves from cathode to accelerating anode should be equal to gain in kinetic energy of electron. Mathematically we can write,

Where, e is the charge on electron,
E is the potential difference between the two plates,
m is the mass of electron,
and v is the velocity of the electron.
Thus, eE is loss in potential energy and 1/2mv1/2 is the gain in kinetic energy.
From equation (1) we have velocity v = (2eE/m)1/2.
Now we have electric field intensity along the y axis is E/d, therefore force acting along the y axis is given by F = eE/d where d is the separation between the two deflection plates.
Due to this force the electron will deflect along the y axis and let the deflection along y axis be equal to D which is marked on the screen as shown in the figure. Due to the force F there is net upward acceleration of the electron along positive y axis and this acceleration is given by Ee/(d × m).Since the initial velocity along positive y direction is zero therefore by equation of motion we can write the expression of displacement along y axis as,

As the velocity along the x direction is constant therefore we can write displacement as,

Where, u is velocity of electron along x axis.
From equations 2 and 3 we have,

Which is the equation of trajectory of the electron. Now on differentiating the equation 4 we have slope i.e.

Where, l is the length of the plate.
Deflection on the screen can be calculated as,

Distance L is shown in the above figure. Final expression of D can be written as,

From the expression of deflection, we calculate deflection sensitivity as,

Graticule: These are the grid of lines whose function is to serve as a scale when the cathode ray oscilloscope is used for the amplitude measurements. There are three types of graticules and they are written below:

1. Internal Graticule:
   Internal graticule as name suggests deposited on the internal surface of the cathode ray tube face plate. There is no problem of parallax errors but we cannot change internal graticules as they are fixed.

2. External graticule:

Given below is the circuit diagram of cathode ray oscilloscope: