The Cathode Ray Tube (CRT)
The constant forces applied to charges by parallel plates allows us to
easily manipulate charges for many practical applications. The Cathode
Ray tube is an excellent example of a device that uses E fields from
parallel plates to manipulate a beam of electrons.
A CRT uses both accelerating plates and deflecting plates as well as a
fluorescent screen to show the location and motion of a beam of
electrons.
We can produce a basic diagram of a CRT as follows:
e
What factors determine the deflection of the beam in the CRT?
1) Find velocity of the beam as it leaves the accelerating plates:
2) Determine the time the beam spends between the plates:
3) Determine the acceleration of the beam in the y direction:
4) Find displacement of the beam in the y direction between the plates:
5) Combine all factors and determine affecting factors
How is dy between the plates related to ∂ seen on the screen?
If the accelerating voltage is doubled but the deflecting voltage is tripled,
what would be the overall effect on the deflection, ∂, seen on the CRT
screen?