Week 5 Homework Assignment

1. Determine the direction of B for each case in Fig.1, where F represent the force on a positively charged particle moving with velocity v.

   

   Fig.1

2. A proton moves in a circular path perpendicular to a 1.15-T magnetic field. The radius of its path is 8.40mm. Calculate the energy of the proton in eV.
3. A long horizontal wire carries 12.0A of current due north. What is the net magnetic field 20.0cm due west of the wire if the Earth's field there points downward, 40° below the horizontal, and has magnitude 5.0 x 10^-5 T?
4. Three long parallel wires are 38.0cm from one another. The current in each wire is 8.00A, but that in wire A is opposite to that in wires B and C (Fig. 2). Determine the magnetic force per unit length on each wire due to the other two. [Hint: Use vector addition to solve the problem.]

   

   Fig. 2