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

Differentiate between a clamper and clipper, Q. What is a clamper? Differen...

Q. What is a clamper? Differentiate between a clamper and clipper. Clamping network shifts (clamps) a signal to a different dc level, i.e. it introduces a dc level to an ac sig

Electronics, determine mimimum SOP for the following swiching funcion using...

determine mimimum SOP for the following swiching funcion using K-map: F(x1,x2,x3,x4)=Summationof m(4,6,8,10,11,12,15)+DC(3,5,7,9)

Permanent magnets, If a permanent magnet creates the flux in a magnetic cir...

If a permanent magnet creates the flux in a magnetic circuit, the flux exists without the need for a coil, so how does Amperes Law apply to this case?   In this case the flux is

Power plant, A power company is developing an upgrade to an existing power ...

A power company is developing an upgrade to an existing power plant and needs to make a requirements decision with respect to the maximum power output capacity for the upgrade. Thi

Diffusion capacitance, Diffusion Capacitance Diffusion capacitance is ...

Diffusion Capacitance Diffusion capacitance is the capacitance because of transport of charge carriers among the two terminals of a device, for instance, the diffusion of carr

Explain multimeter, Explain multimeter A multimeter, or universal instr...

Explain multimeter A multimeter, or universal instrument, may be used to measure voltage, current and resistance.

Draw and explain a monostable multivibrator, Q. Draw and explain a monostab...

Q. Draw and explain a monostable multivibrator ? The monostable configuration consists of two amplifier stages interconnected in such a manner as to possess one stable state. T

Performance equations of three phase induction motor , Performance Equation...

Performance Equations of Three Phase Induction Motor When balanced 3-? voltages are applied to the  stator  winding  a rotating magnetic field  of constant amplitude is produc

Determine the supply current and the supply voltage, A single phase line ha...

A single phase line has an impedance of 8.4 + j11.2 ?. The line feeds a load consisting of a resistor and an inductor connected in parallel as shown in Figure 1. The load is absorb

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