a coil of wire contains of 20 turns, each with an area of 1.5 x 10-3 m2. a magnetic field is normal to the surface of each loop. initially, the magnitude of b is 0.050 t. during the period of time of 0.10 s, the magnitude of the field at the coil has increased to 0.060 t. what is the average emf induced in the coil during this time?