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

Find the new synchronous speed, Q. A wye-connected, three-phase, 50-Hz, six...

Q. A wye-connected, three-phase, 50-Hz, six-pole synchronous alternator develops a voltage of 1000 V rms between the lines when the rotor dc field current is 3A. If this alternator

Example of registers to registers , Example of Registers Example : W...

Example of Registers Example : Write  the instruction to copy  data byte 24H  stored  in register C to register B  Solution : The instruction to copy  data byte  is  a

Differentiate between heat transfer and thermodynamics, Briefly Explain ...

Briefly Explain i. Importance of thermal diffusivity. ii. Describe the laws governing Heat Transfer. iii. Differentiate between Heat Transfer and Thermodynamics iv. Des

Ac circuits, AC Circuit: This topic explain the basic concepts of sing...

AC Circuit: This topic explain the basic concepts of single and three-phase ac system. Unit provides the thorough analysis and derivations as required by topics. Here we find

Compute the speed, Athree-phase,wye-connected, 220-V, 10-hp, 60- Hz, six-po...

Athree-phase,wye-connected, 220-V, 10-hp, 60- Hz, six-pole inductionmotor (using Figure 13.2.6 for notation) has the following parameters in ohms per phase referred to the stator:

Dc machince, what ''s part of dcmotor or dc generator

what ''s part of dcmotor or dc generator

#titl4 bit binary addere.., Ask question #Madvantages of 4 bit binary adder...

Ask question #Madvantages of 4 bit binary adder inimum 100 words accepted#

Ujt as relaxation oscillator, UJT as relaxation oscillator: The UJT re...

UJT as relaxation oscillator: The UJT relaxation oscillator is shown in fig. it consist of a UJT and a capacitor C which is charged through a variable resistance R when VBB is

Branch operations , Branch Operations Normally  the program  executes ...

Branch Operations Normally  the program  executes in  a sequence. The contents of the program counter register are incremented by  one during  the execution  of current  instr

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