Cosmic ray particles entering the Earth’s magnetic field follow spiral paths through
the atmosphere.
In the region of the North Pole, the magnetic field is vertically downwards.
The diagram shows an electron entering a section of uniform magnetic field.
Explain why the electron follows a clockwise spiral path downwards, as seen from above.
(According to FLHR) horizontal force on electron (into the page) (as horizontal component
perpendicular to field)
Or force on electron into the page
Force perpendicular to path results in circular motion
Or Force perpendicular to path acts as centripetal force
Component of motion downwards is unaffected as it is parallel to field lines
Or There are no downward forces so vertical motion is unaffected
