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 n and p type semiconductors, Differentiate between n ...

Differentiate between n and p type semiconductors. n - Type semiconductor:- (i) If small amount of pentavalent impurity is added with, to a pure semiconductor giving a la

Find the rotor current, A 2200-V, 1000-hp, three-phase, 60-Hz, 16-pole, wye...

A 2200-V, 1000-hp, three-phase, 60-Hz, 16-pole, wye-connected, wound-rotor induction motor is connected to a 2200-V, three-phase, 60-Hz bus that is supplied by synchronous generato

Flush plate in residential circuitry, When sizing wire, one of the most dif...

When sizing wire, one of the most difficult tasks is to calculate the electrical load that will be present on the conductors. How do you decide what size wire to use? What two fact

Characteristics of unijunction transistor, Characteristics of  unijunction...

Characteristics of  unijunction transistor: Characteristics : The static emitter characteristic of UJT at a given inter base voltage VBB in shown in fig. From fig., it is no

Calculate the current flow using thevenin''s theorem, Calculate the curren...

Calculate the current flow in 30Ω resistor for the circuit in figure using Thevenin's Theorem.

System diagram of complex programmable logic device, The system diagram for...

The system diagram for the proposed unit is shown below. The system operates on the principle of Time to Rate Conversion. Signals from the heart beat sensor are amplified

Show that operating point does not depend on beta, Q. Prove mathematically ...

Q. Prove mathematically that the operating point does not depend on beta, in a potential divider bias circuit ? To determine the operating point, consider the input section of

Difference among microprocessor and microcontroller, In Microprocessor more...

In Microprocessor more op-codes, few bit handling instructions. But in Microcontroller: fewer op-codes, more bit handling Instructions, and also it is described as a device that ha

Show crystal - oscillator circuits, Q. Show Crystal - Oscillator Circuits? ...

Q. Show Crystal - Oscillator Circuits? The simplest crystal-oscillator circuit is shown in Fig. 6-2A. An equivalent circuit is shown in Fig. 6-2B., where C4 represents the grid

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