Electron beam focused to a fine spot, Electrical Engineering

Assignment Help:

Q. How is the electron beam focused to a fine spot on the face of the CRT?

Sol. The functional diagram of an electrostatic focusing arrangement is shown below. The pre-accelerating anode, which is a metal cylinder containing many baffles, collimates the electron beam which enters it through a small opening on the left hand side. The pre-accelerating anode is connected to a high positive potential.

The focusing anode and the accelerating anodes are co-axial with the pre-accelerating anode. The pre-accelerating and accelerating anodes are connected to the same potential while the focusing anode is connected to a lower potential.

On account of difference of potential between focusing anode and the two focusing anode. The equipotential surfaces thus form a "double concave".

The electron beams entering the field at angles other than the normal to the equipotential surfaces, will be deflected towards the normal and the beam is thus focused towards the centre of the tube axis. By changing the voltage of the focusing anode, the refractive index of the electron lens is changed and therefore the focal point of the beam can be changed. The change in voltage is brought about by chanting the setting of potentiometer. This control is brought to the front panel of CRO and is marked focus.

 

 


Related Discussions:- Electron beam focused to a fine spot

Ac voltage controllers, Q. Explain AC voltage controllers? Common appli...

Q. Explain AC voltage controllers? Common applications for these controllers are found in fan, pump, and crane drives. Figure shows three-phase symmetrical ac voltage-controlle

When mt2 and gate is negative, when MT 2 and Gate  is Negative In th...

when MT 2 and Gate  is Negative In this case gate  current  flows  through P 2 N 3 junction. Junction N 1 P 2 forward  biased hence the triac  starts  conduction through  P

Dc generator, short note on armature reaction

short note on armature reaction

Determine the resultant mmf, Q. The N-coil windings of a three-phase, two-p...

Q. The N-coil windings of a three-phase, two-pole machine are supplied with currents ia,ib, and ic, which producemmfs given by F a = Ni a cos θm; F b = Ni b cos(θm - 120°); and

Illustrate frequency-shift keying, Q. Illustrate Frequency-shift keying? ...

Q. Illustrate Frequency-shift keying? Digital transmission by FSK is a nonlinear modulation method that is appropriate for channels that lack the phase stability needed to perf

Explain the block diagrtam of d.c. voltmeter , Q.   Explain the block diagr...

Q.   Explain the block diagrtam of D.C. voltmeter with direct coupled amplifier. Sol. D.C, voltmeter with direct coupled Amplifier         The D.C. electronic voltmeters

How is segmentation implemented in typical microprocessors, How is segmenta...

How is segmentation implemented in typical microprocessors? The first advantage is as memory segmentation has is that only 16 bit registers are needed both to store segment bas

Absorption of radiation and stimulated emission, Absorption of radiation ...

Absorption of radiation If an atom is initially in a lower state 1, it can rise to a higher stare 2 by absorbing a quantum of radiation. Photon of frequency v where E 1 and E

Determine the flux, Q. Consider themagnetic circuit of Figure. Let the cros...

Q. Consider themagnetic circuit of Figure. Let the cross-sectional area AC of the core, be 16 cm 2 , the average length of the magnetic path in the core lC be 40 cm, the number

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd