Instructions

1. Heat the cathode by sliding the cathode heater to the right and note what happens.
2. Now apply a positive voltage by sliding the anode voltage to the right. Note how the electric field lines change.
3. Adjust the anode voltage again to see what happens when the voltage is so low the electrons do not enter the electric field.

Think about:

• What do you need in order to get a large current from the gun (large number of electrons flowing)?
• What do you need to do to get the electrons flowing faster?