1. TUTORIAL 4 ELECTROMAGNETIC & TRANSFORMER CH. 12 Problems 9, 14 CH. 22 Problems 14, 15

2. Electromagnetic State the methods to increase the strength of the magnetic field around the coil. With aid of diagram, discuss how a magnetic field can induce a voltage in a conductor.

3. CH. 12 Ans. I = 2.13 A

4. CH. 12 19.Find the magnetic flux  established in the series magnetic circuit in Figure Ans. Ф = 6.12 mWb

5. B-H curve for Chapter 12

7. Iron-Core Transformer For the transformer shown in figure 1, calculate: a)maximum flux, ϕ m b)Secondary winding, N s c)Transformation ratio, a d)Current at secondary side, I s if load R L =1 kΩ e)Current at primary side, I p f)Power loss at the load, P loss g)Input resistance of the transformer, Z p

8. = 200 V = 1000 V 100t 500t R L 1kΩ

9. CH. 22 Ans. a. Re = 20 Ω; b. Xe = 40 Ω; c. -; d. Ip = 0.351 A ∟-6.71 o ; e. V L = 28.1 V ∟ -6.71 o ; f. -; g. V L = 30 V; Equivalent Circuit (Iron-Core Transformer)

10. CH. 22 Ans. a. Zp = 360.56 Ω ∟ 86.82 o ; b. Ip = 332.82 mA ∟-86.82 o ; c. V Re = 6.66 V ∟ -86.82 o, V Xe = 13.31 V ∟ 3.18 o, V XL = 106.50 V ∟ 3.18 o ; d. - Equivalent Circuit (Iron-Core Transformer)

11. Fig. 22.60

12. For the transformer in Figure 3, determine: i.The equivalent resistance ii.The equivalent reactance iii.The equivalent circuit reflected to the primary. iv.The primary current. v.The secondary current. vi.The load voltage. vii.The induced voltage in the primary winding. (Hint: Use KVL) viii.The induced voltage in the secondary winding. (Hint: Use KVL)

13. Figure 3