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

Analog communication systems, Q. Analog communication systems? An analo...

Q. Analog communication systems? An analog message is a continuum of possible amplitudes at any given time, and analog signals are continuous in time and in amplitude, such as

Advantages and disadvantages of alloying steel with silicon, State the adva...

State the advantages and disadvantages of alloying steel with silicon for use as magnetic materials in transformer and electric machines. Extensive utilize, is made of iron-sil

Determine the slip at maximum torque, A three-phase induction motor, operat...

A three-phase induction motor, operating at its rated voltage and frequency, develops a starting torque of 1.6 times the full-load torque and a maximum torque of 2 times the full-l

Show the bode plot, Question: (a) Show the Bode Plot, showing the relev...

Question: (a) Show the Bode Plot, showing the relevant corner frequencies and slopes, for the unity feedback system whose open loop transfer function is given by: (b) T

Diffusion current, Diffusion Current : The carrier currents are also ...

Diffusion Current : The carrier currents are also due to concentration gradients in the doped material which lead to diffusion of carriers from high concentration region to l

Calculate the analog output voltag, For the 3-bit 2 n -R D/A converter of ...

For the 3-bit 2 n -R D/A converter of Figure, calculate the analog output voltage when the input is (a) 100, and (b) 010. Solution a. For the binary input 100, switches con

Nodal Analysis, sample problem and solutions with answer

sample problem and solutions with answer

Seal management - meter field testing, Seal Management - Meter Field Testin...

Seal Management - Meter Field Testing For an effective seal management system it is necessary that: i) The  seals  used  are  tamper  proof,  that is they  cannot  be  remo

Inference rules of explanation system, Inference Rules of Explanation syste...

Inference Rules of Explanation system How an Explanation System might work where questions like how or why are dealt with. Inference Rules use an if-statement and a then-statem

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