A very long, straight solenoid with a cross-sectional area of 6.10 cm2 is wound with 42 turns of wire per centimeter, and the windings carry a current of 0.235 Amp. A secondary winding of 2 turns encircles the solenoid at its center. When the primary circuit is opened, the magnetic field of the solenoid becomes zero in 4.90 x 10-2 second.
Obtain the average induced emf in the secondary coil?