How electron get deflected in magnetic field while moving? I don't understand why electron moves this way... e.g. A light object (crampled paper) going down until gets hit by the wind will go parallel (at least a few seconds) to the wind direction ... why not with electron?
 
 A: For electrons the magnetic field is not like a "wind". The electron experiences a velocity dependent force, the Lorentz force, which is perpendicular to both the direction of the velocity and to the magnetic field direction. See, e.g., https://en.wikipedia.org/wiki/Lorentz_force .
A: Some basics at the beginning:


*

*an electron, moving parallel to a magnetic field won't be deflected

*a positron as well as a proton will be deflected in the opposite direction to the direction of an electron or a antiproton

*during deflection these particles emit photons

*loosing energy these particles slowing down, the deflection will has a spiral path and at the end the particles get stopped.


Another important facts:


*

*all these particles have magnetic dipole moments and an intrinsic spin

*due to the Einstein-de Haas-experiment this spin has an angular momentum

*the axis of the spin and the direction of the magnetic dipole moment are parallel or antiparallel

*is parallel and antiparallel is a convention, but if for an electron it will be defined as parallel, than for a antiproton it is also parallel (and the antiproton will be deflected in the same direction as the electron) and for positrons and protons it will be antiparallel



How electron get deflected in magnetic field while moving

To stick it together one has to recognise that the external magnetic field will align the electrons magnetic dipole moment, this led to the emission of photons, this to a disalignment and ... The game starts again as long as the electron has kinetic energy. More in detail see my elaboration About the internal cause of Lorentz force
A: The answer is in your diagram, but it might not be obvious.
To start with, in your example you have the wind moving, but a static magnetic field. That is not the same. A correct analogy would be to turn the fan off. So in that case, the "light object" would simply fall right through the area between N and S.
Now recall that electrons are spinning (well, sort of). So let us spin the "light object", very rapidly. Now as it drops the spinning will entrain the air, a fluid, and cause a force at right angles to it's motion. This is due to the Magnus effect (well, sort of) and you can see it working here, which would go around in circles except for the rudder.
And that's basically the answer. The electron is "spinning" at a ridiculous rate and passing through a medium that is effectively a perfect fluid. The interaction between the two causes a force that is at right angles to the direction of motion.
