(a) Describe in words, and with the aid of your own diagram, the form of the magnetic field due to the current, i, in the wire. Use the magnetic field lines to indicate roughly how the field varies with increasing distance from the
wire. (6 marks)
(b) A particle with charge q moves with velocity v near the wire. Give an expression for the magnitude of the force on this particle in terms of q, v = | v | and the magnitude of the magnetic field strength B. Make sure you define any other variables that you introduce. (2 marks)
(c) Suppose the particle has a charge q = 2.5 Î¼C and is moving with a velocity of magnitude v = 1.0 Ã— 103 m sâˆ’1, in a direction parallel to the wire and in the same direction as the current. The particle is at distance d = 1.5 mm from the wire and experiences a force of magnitude 1.0 Ã— 10âˆ’6 N. Calculate the current in the wire. Draw a diagram to indicate the direction of the force on the particle. (13 marks)
(d) Suppose the particle has an additional component of velocity parallel to the magnetic field. Explain in a couple of sentences how this would change the force.