1. Thermoionic Emission

Heat up water and it evaporates, if we do the same to a metal filament then we can 'boil' off electrons which we then accelerate with a positive potential difference - this is our thermionic emission which is so useful for many other applications.

 

2. Forces on a moving charge

When a moving charge is in an electric or a magnetic field it experiences a force - this is just revision of a topic you will have covered previously in A Level Physics.

 

3. Electron Tubes

In this video I just discuss the main types of tubes you may find in a physics lab. The Maltese Cross, Deflection, Perrin, Electron Diffraction and finally (the only one I don't have) the fine beam tube.

 

4. Measuring the Charge to Mass with a Deflection Tube

A full on video - but follow this to see how the charge to mass ration for electrons can be found from a deflection tube. Firstly you balance the forces to allow the cathode ray to go straight through, you can then use either field to find the result you're after.

 

5. Measuring the Charge to mass with a fine beam tube

Following on from the last video this is another way to measure e/m in the lab - this time using a different type of tube.

 

6. Thomson's Value of e/m

What is the significance of Thomson's value of e/m and how did it compare to what was known at the time?

 

7. Millikan's Oil Drop Experiment

A long video but I show you what Millikan did to measure the elementary charge on an electron, including how Stoke's Law can be used to calculate the radius of the droplet.