Hydrothermal power plants use the heat from deep within the Earth’s surface to produce

(Q1b) A separately excited de generator has a no-load voltage of 100 V. We increase the excitation current by 10%. What voltage would we measure in the terminals? (a) 100 V, (b) 107 V, (c) 110 V, (d) 113 V

1 A flux of 30 mWb links with a 1200 turn coil when a current of 5 A is passing through the coil. Calculate (a) the inductance of the coil, (b) the energy stored in the magnetic field, and (c) the average e.m.f. induced if the current is reduced to zero in 0.20s [(a) 7.2 H (b) 90J (c) 180 V] 2 An e.m.f. of 2 kV is induced in a coil when a current of 5 A collapses uniformly to zero in 10 ms. Determine the inductance of the coil. [4 H]

Consider the magnetic circuit shown below. The primary coil has N1=400 turns, and the secondary coil has N2=800 turms. The total length of the core (shown in red) is 5 cm. The core has a uniform cross section 2 cm2 , magnetic permeability 900. Calculate the total inductance between terminals a and b, if the coils are connected as shown below. Assume that there is no flux leakage from the core. N1 N2