Over and over I'm getting into the same trouble, so I'd like to ask for some help.
- I need to solve some basic electrodynamics problem, involving magnetic fields, moving charges or currents.
- But I forgot all this rules about "where the magnetic field should go if the current flows up". I vaguely remember that it about hands or fingers or books or guns, and magnetic field should go somewhere along something, while current should flow along something else... But it doesn't help, because I don't remember the details.
- I do find some very nice rule and use it. And I think "that one I will never forget".
- ...time passes...
- Go to step 1.
The problem is that you have to remember one choice from a dichotomy: "this way or that way". And all the mnemonics I know have the same problem -- I got to remember "left hand or right hand", "this finger or that finger", "inside the book or outside of the book".
Maybe someone knows some mnemonics, that do not have such problem?