Electron Optics Model Questions

Source:  Electron Optics Model Questions    Tag:  block diagram of cathode ray tube
Unit 2 - Electron Optics - One mark Questions

1) The bending of electrons by electric fields is called
a) Electron reflection
b) Electron refraction
c) Electron diffraction
d) Electronic bending
Ans: b

2) The most important component of an electron gun used for producing a narrow intense electron beam is
            a) Electron lens
            b) Electric field
            c) Glass lens
            d) Both a and c
Ans: a

3) The component used in the electron microscope which can converge an electron beam but cannot be used for diverging action. What is it?
            a) Electron lens
            b) Magnetic lens
            c) Fluorescent screen
d) Both a and b
Ans: b



4) The inner surface of the flare of the glass envelope of CRT (Cathode Ray Tube) is coated with conductive graphite coating called
            a) Acquadag
            b) Acquabag
            c) Radium
            d) None of the above
Ans: a

5) The interior surface of circular front of the CRT is coated with a thin translucent layer of fluorescent material. What is it?
            a) Phosphor
            b) Sulphur
            c) Radium
            d) Magnesium
Ans: a

6) What is the name of the transparent graph attached to the face of the CRT used for making measurements?
            a) Graticule
            b) Granule
            c) Graph
            d) Grains
Ans: a

7) What is the method of locking the frequency of the time base generator to the frequency of the input signal so that a stationary display of wave pattern is seen on the CRO screen?
            a) Deflection
            b) Synchronization
            c) Sweeping
            d) Triggering
Ans: b

8) ____________ is the only instrument that can give a visual display of the actual shape of the signal
            a) CRT
            b) Trigger circuit
            c) CRO
            d) None of the above
Ans: c

9) The trapped particles form radiation belts around the earth are called______
            a) Van Allen belts
            b) Magnetic belts
            c) Coastal belts
            d) Both a and b
Ans: a

10) Snells law describes refraction of light whereas Bethe’s law deals with
            a) Electron reflection
            b) Proton refraction
            c) Electron refraction
            d) Coherence of Laser
Ans: c


11) In the CathodE Ray Tube, the time taken by the sweep voltage to dip from its positive maximum to negative maximum value is called
            a) Fly back time
            b) Sweep period
            c) Trace time
            d) None
Ans: a

12) ________________ is used in Bainbridge mass spectrograph for separating positive ions of different masses.
            a) Velocity selector
            b) Momentum selector
            c) Isotope selector
            d) None
Ans: b

13) Beams of electrons can be deflected by electric and magnetic fields. Write True or False.
            a) True           b) False
Ans: True

14) The intrinsic property of the electron spin s is equals to 1/2. Answer True or False
a) True              b) False
Ans: True





15) In an external magnetic field the force of the electron is given by
                                     where v represents the
            a) Velocity of the electron
            b) Amplitude of the electron
            c) Frequency of the electron
            d) Magnetic field of the electron
Ans: a

Four mark questions
1) Discuss refraction of electron beam across an equipotential surface.
2) What is Bethe’s law? In what way it resembles and differs the Snell’s law.
3) Explain the working of electrostatic electron lens.
4) Explain the principle and construction of electron gun with neat diagram.
5) Draw the neat diagram of cyclotron and explain its principle and construction.
6) Draw the block diagram of CRO and discuss two applications.
7) Explain the working of magnetic lens.
8) Explain the principle of Bainbridge mass spectrograph with neat sketch.
9) Explain the construction of electron microscope with neat diagram.
10) Calculate the maximum energy to which deuterons can be accelerated in the cyclotron.
Given data are
            Magnetic Induction, B = 1.57 T
            Oscillator frequency, v = 12 x 106 Hz
            Radius of the Dee, R = 21 Inch/0.53m
            Deuteron Charge, q = 1.602 x10-19 C
Deuteron mass, md = 3.34 x 10-27 kg