A 500 turn solenoid has a length of 25 cm and a radius of 2.0 cm. It carries a current of 4.0 A. A second solenoid of 10 turns is tightly wound around the 500-turn solenoid such that it has the same radius as the 500-turn solenoid.
a) Find the magnitude of the average induced emf ? in the second coil when the current in the 500-turn solenoid increases to 10.0 A in a period of 1.2 s.
b) What is the direction of the induced magnetic field in the second solenoid with respect to the direction of the magnetic field of the 500-turn solenoid?
c) If the current now drops back to 4.0 A in 2.4 seconds what is the magnitude of the average induced emf ? in the second coil and what is the direction of the induced magnetic field in the second solenoid with respect to the direction of the magnetic field of the 500-turn solenoid?