2. An iron core 0.4 m long and 5 square cm. in cross-section, is wound with 300
turns. When a current of 0.5 A flows in the coil, how much is the inductance of
the coil. Assume the core has a permeability of 2,500.
Answer: L = 0.35 H
3. Two coils having 200 and 300 turns respectively are wound side by side on a
common closed core whose cross-section is 100 cm2 and mean length of 200
cm. What will be the voltage induced in the second coil if the current in the
first coil changes from 0 to 5 A in 0.05 second. Assume the relative permittivity
of the core to be 1,500.
Answer: e2 = 67.8 V