A 35 cm long straight conductor carries a current of 6 A and is pushed at a constant speed of 4 cm s⁻¹ into a region of uniform magnetic field that extends over a width of 20 cm. The field is perpendicular to the conductor. The leading end of the conductor enters the field at t=0s.
a. (i) Write an expression for the length l(t) of the conductor that is inside the field for 0≤t≤5s. Clearly state any conditions used.
b. (ii) Using this result, calculate the magnetic force acting on the conductor at t=3s if the magnetic field strength is 0.35 T.