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Worksheets4.1 Thermionic Emission
Total questions: 20
Worksheet time: 9mins
Process of emission of electrons from hot metal surfaces is called .................
photoelectric effect
thermionic emission
static emission
emission current
Which particle escapes from the surface of the metal when it is heated at a high temperature?
Proton
Neutron
Nucleon
Electron
Which particle is cathode ray?
Electron beam
Gamma ray
Neutron
Alpha particles
One of the properties of cathode rays is ...............
positive charge
does not move in a straight line
can be deflected by electrical field
cannot be deflected by magnetic field
If an electric field is put across the beam with the positive plate on top and the negative plate below.
The beam will bend ...............
Up
down
left
right
in a circle
Cathode rays carry ..........
negative charge
positvie charge
neutral particles
electrons and protons
I use thermionic emission to emit a stream of electrons and display them on a screen.
Cathode-Ray Oscilloscope
Raster-Scan Display
Random-Scan Display
Why is a vacuum needed in the tube?
It makes the process more efficient.
It impedes or slows down the electrons.
It allows the electrons to flow unimpeded.
It allows the electrons to be made into a beam.
How is the electron beam detected?
Use of a fluorescent screen.
By deflecting the beam of electrons with a magnetic field.
By deflecting the beam of electrons with an electric field.
Using an electron microscope.
What happens when cathode rays strike the fluorescent screen ?
electron bounces back
nothing happens
emit light
produce current
how to increase the rate of thermionic emission
immerse metal in an electrolyte
increase the surrounding pressure
decrease the temperature of metal to stabilize electron
increase the surface area of the metal
What can be used to control the direction of the cathode ray?
electrical field
gravitational field
heat energy
quantum field
What is the purpose of connecting anode with high voltage d.c power supply?
to deflect or change the direction of the electron
to accelerate the electron
to deceleration the electron
to increase the rate of thermionic emission
X-plates is
positioned vertically to deflect the electron beam in horizontal direction
positioned horizontally to deflect the electron beam in vertical direction
Diagram shows part of C.R.O. What is Q?
Control grid
Focusing anode
Accelerating anode
Cathode
What you need to control in order to adjust the brightness of the signal in C.R.O.?
Focusing anode
Control grid
Accelerating anode
Cathode
Which of the following is wrong about the uses of C.R.O.?
To measure potential difference
To measure short time intervals
To display waveforms
To measure current
What is the function of time-base knob on C.R.O.?
To control brightness of the bright spot
To control the sharpness of the bright spot
To control the magnitude of vertical deflection of the bright spot
To control the magnitude of horizontal deflection of the bright spot
Tick the statement about uses of CRO. Your answer may have more than 1.
measure potential difference using the C.R.O.
measure short time intervals using the C.R.O.
display wave forms using the C.R.O.
