An electron from the sun with a speed of 1 × 10⁷ m/s enters the earth's magnetic field high above the equator where the magnetic field is 4 × 10^–7T. The electron moves nearly in a circle except for a small drift along the direction of the earth's magnetic field that will take it toward the north pole.

1. (a) What is the radius of the circular motion?

(b) What is the radius of the circular motion near the north pole where the magnetic field is 2 × 10^–5 T?

2. What orientation of a current loop gives maximum torque?