This section is devoted to the interaction of cosmic rays and magnetic fields of Astrophysical objects.

A set of Geogebra activities (a. and b.) are proposed in order to become familiar with the main aspects of the magnetic force.

Part c. is entirely dedicated to the relation between the momentum and the curvature radius of a charged particle moving in a uniform magnetic field. Furthermore the momentum usual particle physics units (eV/c) are introduced.

In part d. the physics of magnetic interactions becomes the tool to figure out possible astrophysical sources of extreme energy cosmic rays. The "Knee" in the Cosmic Rays Spectrum is explained in unit e.

a. MAGNETIC FORCE

b. INFLUENCE OF THE SIGN OF THE CHARGE ON THE TRAJECTORY DIRECTION

c. DETERMINE THE MOMENTUM OF PARTICLES FROM THE RADIUS OF CURVATURE OF THE TRACKS

d. ASTROPHYSICAL CANDIDATES FOR EXTREME ENERGY COSMIC RAYS

e. UNDERSTANDING THE "KNEE"