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
Sir! Question number 15?
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