Work Step by Step
Charged particles moving in a magnetic field are deflected the most when they move at right angles to the field lines, and deflected the least when they move parallel to the field lines. This is stated on page 460. Cosmic rays (high-energy charged particles) that are heading toward regions near the Earth's poles (such as northern Canada) are moving more parallel to the Earth's magnetic field lines (see Figure 24.20), and are deflected less. This is shown in Figure 24.14. For regions closer to the equator (such as Mexico), incoming cosmic rays move more nearly at right angles to the Earth’s magnetic field, and are deflected away.