Steering Electrons in a Cathode ray Tube.

How the electons are focused and accelerated forwards in the cathode ray oscilloscope?
- Albert Lau (age 17)
Malaysia

Good question.  The electrons start out from an electrode called a cathode.  They are boiled out of a metal by heating it up to a high temperature.   The electrons are then attracted to another electrode, called the anode, by means of an electric field caused by applying a positive voltage between the cathode and the anode.     The electrons can be deflected by applying a transverse electric or magnetic force field.    Focusing can be obtained by means of a clever arrangement of field gradients.  The technical term is a quadrupole field.  
You can find some more information at 
A nice historical article can be found at

LeeH

(published on 06/19/2008)