Practice Test: Question Set - 07
1. In a step-down transformer, there is a change of 15 A in the load current. This results in change of supply current of
- (A) Less than 15 A
- (B) More than 15 A
- (C) 15 A
- (D) None of the above
2. A certain amplifier has 600 Ω internal resistance looking from its output. In order to provide maximum power to a 4 Ω speaker, what turns ratio must be used in the coupling transformer?
- (A) 8
- (B) 0.8
- (C) 0.08
- (D) 80
3. A step-up transformer steps up power.
- (A) True
- (B) False
4. Which of the following insulating materials can withstand the highest temperature safely?
- (A) Cellulose
- (B) Asbestos
- (C) Mica
- (D) Glass fibre
5. 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
6. In a transformer the resistance between its primary and secondary should be
- (A) Zero
- (B) 10 Q
- (C) 1000 Q
- (D) Infinity
7. A transformer transforms
- (A) Voltage
- (B) Current
- (C) Current and voltage
- (D) Power
8. For the parallel operation of single phase transformers it is necessary that they should have
- (A) Same efficiency
- (B) Same polarity
- (C) Same kVA rating
- (D) Same number of turns on the secondary side
9. Negative voltage regulation is indicative that the load is
- (A) Capacitive only
- (B) Inductive only
- (C) Inductive or resistive
- (D) None of the above
10. The efficiency of a transformer will be maximum when
- (A) Copper losses = hysteresis losses
- (B) Hysteresis losses = eddy current losses
- (C) Eddy current losses = copper losses
- (D) Copper losses = iron losses