The current in the primary coil of a pair of coils changes from 7 A to 3 A in 0.04 s. The mutual inductance between the two coils is 0.5 H. The induced emf in the secondary coil is -

A coil of area 100 cm² is kept at an angle of 30$$^\circ$$ with a magnetic field of 10^$$-$$1 T. The magnetic field is reduced to zero in 10^$$-$$4 s. The induced emf in the coil is -