1. The neutron is a particle with zero charge. However, it has a nonzero magnetic moment of 9.66 × 10-27Am2. A possible explanation for this is the circular motion of 'quarks' - fundamental subatomic particles. The neutron is believed to consist of an "up" quark with a charge of +2e/3 and two "down" quarks each of charge -e/3 (note net charge is still zero). If the quarks are in motion they can create a magnetic moment. In particular, the magnetic moment produced by a circular current is µ = IA, where I is the current and A is the area of the circle.
The radius of the neutron is 1.2 × 10-15m and so this seems a reasonable estimate for the radius of the orbits. If the up quark moves around in one direction, and the down quarks move in the opposite direction, all with the same speed v how fast will they have to be moving to generate the observed magnetic moment?