H Exp – Electricity and Electronics 02 – The Cathode Ray Tube

Aim – To investigate the path of the electron beam in a cathode ray tube.

Instructions

▪ Note the value of the EHT voltage used in the electron gun.
▪ Calculate the work done on each electron by the electric field in the electron gun.
▪ Hence calculate the speed of the electrons as they leave the electron gun and enter the evacuated tube.
▪ Switch the HT supply ON. Sketch the path followed by the electron beam as it passes between the deflection plates when:
▪ a) bottom plate is positive, top plate is negative
▪ b) top plate is positive, bottom plate is negative
▪ Explain the effect the following changes have on the path followed by the electron beam:
▪ a) increase EHT voltage on the electron gun
▪ increase HT voltage on the deflection plates.

▪ Wait for Player to load. Best viewed full screen, right-click or on mobile, press and hold and select Enter full screen. Full screen not available on iOS.