CATHODE-RAY
OSCILLOSCOPE (C.R.O)
OSCILLOSCOPE (C.R.O)
Definition:
The cathode-ray oscilloscope is an
instrument which is used to display the magnitudes of changing electric
currents or potentials
instrument which is used to display the magnitudes of changing electric
currents or potentials
The cathode-ray oscilloscope (C.R.O)
consists of the following components:
consists of the following components:
•The
electron gun with control grid
electron gun with control grid
•The
deflecting plates
deflecting plates
•A
fluorescent screen
fluorescent screen
The
Electron Gun
Electron Gun
The electron gun consists of an electron
source which is an electrically heated cathode that ejects electrons.
source which is an electrically heated cathode that ejects electrons.
Grid
G:
G:
Electron gun also has an electrode called
grid G for controlling the flow of electrons in the beam. The grid is connected
to a negative
potential.
grid G for controlling the flow of electrons in the beam. The grid is connected
to a negative
potential.
Function
Of Grid:
Of Grid:
The more negative this potential, the
more electrons will be repelled from the grid and hence fewer electrons will
reach the anode and the screen The number of electrons reaching the screen
determines the brightness of the screen. Hence, the negative potential of the
grid can be used as a brightness control.
Anode:
The anode is connected to positive potential and hence is used to accelerate
the electrons. The electrons are focused into a fine beam as they
pass through the anode.
more electrons will be repelled from the grid and hence fewer electrons will
reach the anode and the screen The number of electrons reaching the screen
determines the brightness of the screen. Hence, the negative potential of the
grid can be used as a brightness control.
Anode:
The anode is connected to positive potential and hence is used to accelerate
the electrons. The electrons are focused into a fine beam as they
pass through the anode.
The
Deflecting Plates:
After
leaving the electron gun, the electron beam passes between a pair of horizontal
plates.
Deflecting Plates:
After
leaving the electron gun, the electron beam passes between a pair of horizontal
plates.
A
potential difference applied between these plates deflects the beam in a
vertical plane.
potential difference applied between these plates deflects the beam in a
vertical plane.
•
•This
pair of horizontal plates provides the
Y-axis or vertical movement of the spot on the screen.
pair of horizontal plates provides the
Y-axis or vertical movement of the spot on the screen.
• A
pair of vertical plates provides the X-axis or horizontal movement of the spot
on the screen
pair of vertical plates provides the X-axis or horizontal movement of the spot
on the screen
The Fluorescent Screen
The
screen of a cathode-ray tube consists of a thin layer of phosphor, which is a
material that gives light as a result of bombardment by fast moving electrons.
The
screen of a cathode-ray tube consists of a thin layer of phosphor, which is a
material that gives light as a result of bombardment by fast moving electrons.
Applications:
The CRO is used in many fields of science; displaying
waveforms, measuring voltages, range-finding (as in radar), echo-sounding (to
find the depth ofseabeds).
The CRO is used in many fields of science; displaying
waveforms, measuring voltages, range-finding (as in radar), echo-sounding (to
find the depth ofseabeds).
The CRO is also used to display
heartbeats.
heartbeats.
When a magnet is brought near to
the screen of a
television tube, picture on the screen is distorted. Do you know why?
the screen of a
television tube, picture on the screen is distorted. Do you know why?
Electromagnets are used to deflect
electrons to desired positions on the screen of a television tube
electrons to desired positions on the screen of a television tube
No comments:
Post a Comment