(a) The magnetic field at the centre of a solenoid of length 12 cm carrying a current of 4 A is 4x x 10-4 T. What is the total number of turns of the solenoid? (2 marks) (b) A plane of circular loop of wire with diameter 3.4 cm is parallel to a 0.87 T magnetic field. The loop carries a current of 3.0 A. Find the torque that acts on the loop. (3 marks) (c) An electron at point A in Figure Q3(c) has a speed ofv = 1.41 x 10 my-]. Find: 10.0 cm Figure Q3(c) (i) the magnitude and direction of the magnetic field that will cause the electron to follow the semicircular path from A to B, and (3 marks) (ii) the time required for the electron to move from A to B