Interactions between particles
So far in the course we have introduced the proton, neutron, photon, neutrino and electron so best to start by classifying them and the interactions they take part in.
Probably worth memorising relative strength and range of the different forces.
Although throwing a sack of potatoes from one canoe to another isn't a correct picture of an exchange force it gets the idea across and the introduction of a boomerang adds a bit of fun. HL student will know about Heisenbergs uncertainty principle so can understand why virtual particles have to be short lived.
Students only need to deal with simple, one vertex Feynman diagrams (hopefully). The two electron - one photon example shows nicely how interactions can be predicted by rotating the arms.
I have been trying to find an applet for building Feynman diagrams but can't find one, here is an animation (time on the y axis). In the end I made my own simple version in GeoGebra.
pages 313 - 316
Exercises 36 - 37
Feynman diagrams in GeoGebra
Move the electron and positron around to make different interactions. I couldn't make a wavy line so you have to make do with a dashed one for a photon.
And with 4 particles