Page 524 - Basic Electrical Engineering

[Ans I = 3.3 A]

2
18. An iron ring of mean diameter of 10 cm and cross-sectional area of 8 cm is wound with a
wire having 300 turns. The permeability of iron is 500. What current should be passed through
2
the winding wire so that a flux density of 1.2 Wb/m is produced in the core?

[Ans I = 2A]

19. Fig. 5.34 shows a magnetic circuit. Calculate the current required to be passed through the
central limb winding so as to produce a flux of 1.6 mWb in this limb. Length of iron in the
2
central limb is 15 cm. Cross-sectional area of the central limb is 8 cm and that of the outer
2
limbs is 4 cm .

Figure 5.34

The mean length of iron of the outer limbs is 32 cm each. Given that for iron for a flux density
2
of 2.0 Wb/m the value of H is 800 AT/m.

[Ans I = 1.905 Ampere]

C. Multiple Choice Questions

1. A magnetic circuit and an electric circuit can be compared as

a. flux is analogous to current
b. reluctance is analogous to resistance
c. MMF is ≠ analogous to EMF
d. all these as in (a), (b), and (c).

2. The relationship of flux, reluctance and MMF is

a.