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ELE 1201 MICHAEL FRASER WORKSHEET # 3 1. In the magnetic system of the Figure below two sides are thicker than the other two sides. The depth of the core is 10 cm, the relative permeability of the core, ur = 2000, the number of turns N = 500, and the current flowing through the coil is i = 1 A. (a) Determine the flux in the core.

(b) Determine the flux densities in the parts of the core.
(c) Find the current i in the coil to produce a flux (φ=0.012Wb).

2. A circular ring of magnetic material has a mean length of 1.0 m and a cross-sectional area of 0.001 m2. A saw cut of 5 mm width is made in the ring. Calculate the magnetizing current required to produce a flux of 1.0 mWb in the air-gap if the ring is wound uniformly with a coil of 200 turns. Take relative permeability of the ring material =500 and neglect leakage and fringing.

3. A ring of mean diameter 21 cm and cross-section 10 cm2 is made up of semi-circular sections of cast steel and cast iron. If each joint has reluctance equal to an air gap of 0.2 mm as shown in Fig. find the Amp. turn required to produce a flux of 45*10− weber in the magnetic circuit. Take ur for steel and iron as 825 and 165 respectively: Neglect leakage and fringing

4. Two coils are wound on a toroidal core as shown in Fig. The core is made of silicon sheet steel and has a square cross section. The coil currents are i1 = 0.28 A and i2 = 0.56 A. (a) Determine the flux density at the mean radius of the core. (b) Assuming constant flux density (same as at the mean radius) over the cross section of the core, determine the flux in the core.

(c) Determine the relative permeability,

5. The magnetic circuit of Fig. provides flux in the two air gaps. The coils (N1 = 700, N2 = 200) are connected in series and...
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