(d) Consider a straight wire of length 1, and cross sectional area A, carrying a current I, in a uniform magnetic field B. The angle between the direction of current flow and the magnetic field is 0. If the current is given by I = nqvdA, where n is the number of charges per unit volume, and va is the drift velocity of the charges, each of which has a value of q coulombs, derive an expression for the force on the wire due to the current flowing in the magnetic field. (3 marks)