Faraday's second law of EMI says that the magnitude of e.m.f. induced in a cuicuit is directly proportional to the rate of change of magnetic flux linked with circuit, i.e., `e prop (d phi)/(dt)`. It means if the magnetic flux linked with a circuit changes at a faster rate, the induced e.m.f. is larger and vice-versa.
Read the above passage and answer the following question :
(i) Coil A is held in a very strong magnetic field and coil B is held in a weak magnetic field. In which coil do you expect larger induced e.m.f. ?
(ii) A coil is moved in a uniform magnetic field. When do you expect induced e.m.f. in the coil ?
(iii) What values of life do you learn from Faraday's second law of EMI ?

Explanation

Induced e.m.f. in both the coils is zero. This is because magnetic flux linked with A or B is not changing, Magnetic flux linked with A is larger and magnetic flux linked with B is smallar. But amount of magnetic flux linked with the coil does not induce e.m.f. in the coil. The magnetic flux must change to induce e.m.f.
(ii) Induced e.m.f. would develop in the coil, when it is entering the magnetic field or leaving the magnetic field, i.e., when the coil is partially in the magnetic field and partially out of magnetic field. This is because magnetic flux linked with the coil would change only in these situations When the entire coil is moving in the magnetic field, magnetic flux linked with the coil is constant, but it is not changing therefore, there is no induced e.m.f. in the coil.
(iii) In day to day life, rate of change of magnetic flux linked with a circuit corresponds to the rate of activity/effort made by us and induced e.m.f. is a measure of our success/output/achievement.
The law implies that our output/success/achivenment varies directly with the rate of our activity/effort/input. Faster in the inpur, greater is the output. This is so ture in daily life.