### Electrical Machines Quiz (Transformer)

1. What kVA rating is required for a transformer that must handle a maximum load current of 8 A with a secondary voltage of 2 kV?

A. 4 kVA

B. 0.25 kVA

C. 16 kVA

D. 8 kVA

2. The turns ratio required to match an 80 source to a 320 load is

A. 80 B. 20

C. 4 D. 2

3. When the turns ratio of a transformer is 20 and the primary ac voltage is 12 V, the secondary voltage is

A. 12 V

B. 120 V

C. 240 V

D. 2,400 V

4. If a transformer has 50 turns in the primary winding and 10 turns in the secondary winding, what is the reflective resistance if the secondary load resistance is 250 ?

A. 250

B. 25

C. 6,250

D. 62,500

5. A certain transformer has 400 turns in the primary winding and 2,000 turns in the secondary winding. The turns ratio is

A. 0.2

B. 0.4

C. 5

D. 25

6. The primary winding of a transformer has 110 V ac across it. What is the secondary voltage if the turns ratio is 8?

A. 8.8 V

B. 88 V

C. 880 V

D. 8,800 V

7. To step 110 V ac down to 20 V ac, the turns ratio must be

A. 5.5

B. 18

C. 0.18

D. 0.018

8. The mutual inductance when k = 0.65, L1 = 2 H, and L2 = 5 H is

A. 2 mH

B. 2 H

C. 4 H

D. 8 H

9. If 25 W of power are applied to the primary of an ideal transformer with a turns ratio of 10, the power delivered to the secondary load is

A. 25 W

B. 0 W

C. 250 W

D. 2.5 W

10. A transformer with a 110 V primary has a 15:1 turns ratio. The load resistance, RL, is 120 . What is the approximate voltage across the load?

A. 7.3 V

B. 73 V

C. 88 V

D. 880 V

1. c

2. d

3. c

4. c

5. c

6. c

7. c

8. b

9. a

10. a

A. 4 kVA

B. 0.25 kVA

C. 16 kVA

D. 8 kVA

2. The turns ratio required to match an 80 source to a 320 load is

A. 80 B. 20

C. 4 D. 2

3. When the turns ratio of a transformer is 20 and the primary ac voltage is 12 V, the secondary voltage is

A. 12 V

B. 120 V

C. 240 V

D. 2,400 V

4. If a transformer has 50 turns in the primary winding and 10 turns in the secondary winding, what is the reflective resistance if the secondary load resistance is 250 ?

A. 250

B. 25

C. 6,250

D. 62,500

5. A certain transformer has 400 turns in the primary winding and 2,000 turns in the secondary winding. The turns ratio is

A. 0.2

B. 0.4

C. 5

D. 25

6. The primary winding of a transformer has 110 V ac across it. What is the secondary voltage if the turns ratio is 8?

A. 8.8 V

B. 88 V

C. 880 V

D. 8,800 V

7. To step 110 V ac down to 20 V ac, the turns ratio must be

A. 5.5

B. 18

C. 0.18

D. 0.018

8. The mutual inductance when k = 0.65, L1 = 2 H, and L2 = 5 H is

A. 2 mH

B. 2 H

C. 4 H

D. 8 H

9. If 25 W of power are applied to the primary of an ideal transformer with a turns ratio of 10, the power delivered to the secondary load is

A. 25 W

B. 0 W

C. 250 W

D. 2.5 W

10. A transformer with a 110 V primary has a 15:1 turns ratio. The load resistance, RL, is 120 . What is the approximate voltage across the load?

A. 7.3 V

B. 73 V

C. 88 V

D. 880 V

**Answers:**1. c

2. d

3. c

4. c

5. c

6. c

7. c

8. b

9. a

10. a

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