Jawaharlal Nehru Technological University Hyderabad B.Tech II Year FUNDAMENTALS OF ELECTRICAL ENGINEERING Previous Question Paper (March - 2021 - R13)

(i) Self Inductance is the property of a coil by which it opposes any change in the current flowing through it. It is defined as the ratio of flux linkage to the current producing it, measured in Henrys (H).

(ii) Mutual Inductance is the property by which a change in current in one coil induces an electromotive force (e.m.f) in an adjacent coil due to magnetic coupling.

(iii) Magnetomotive Force (MMF) is the magnetic analogue of electromotive force in an electric circuit, defined as the product of the number of turns (N) and the current (I) flowing through the coil, measured in Ampere-turns (AT).

(iv) Magnetic Flux is the total number of magnetic field lines passing through a given area, represented by the symbol Φ and measured in Webers (Wb).

(v) Reluctance is the opposition offered by a magnetic circuit to the establishment of magnetic flux, defined as the ratio of MMF to flux, measured in AT/Wb.

Given: Mutual Inductance (M) = 0.4 H, Change in current (dI) = 2A - 4A = -2A, Time interval (dt) = 0.5 s, Number of turns (N) = 300.

1. The average induced e.m.f (e) in the second coil is given by the formula:
   e = -M * (dI / dt)
   Substituting the values: e = -0.4 * (-2 / 0.5) = 1.6 V.
2. The induced e.m.f is also related to the rate of change of flux (dΦ/dt) by Faraday's law:
   e = N * (dΦ / dt)
   Rearranging for the rate of change of flux:
   dΦ / dt = e / N
   Substituting the values: dΦ / dt = 1.6 / 300 = 0.00533 Wb/s.