ECET EEE 2012-7

1. The 2's complement of the number 1001 1100 is

A. 0110 0011
B. 0110 0100
C. 1001 1100
D. 1001 1101

Answer : B. 0110 0100
Explanation:-

2. The boolean expression for NOR gate with inputs A and B is

A. A+B
B. AB
C. A-B
D. (A+B)'

Answer : D. (A+B)'
Explanation:-

3. A DAC with 8 input bits has _____ resolution compared with DAC with 4 input bits

A. High
B. Same
C. Low
D. Infinite

Answer : A. High
Explanation:-

4. The power electronic device, silicon controlled rectifier has

A. two junctions and three layers
B. three junctions and three layers
C. three junctions and four layers
D. two junctions and two layers

Answer : C. three junctions and four layers
Explanation:-

5. Which one of the following is a bilateral controlled switch

A. Thyristor
B. Triac
C. GTO
D. Diac

Answer : C. GTO
Explanation:-

6. If the gate current of an SCR is increased, its forward break over voltage VBO will

A. Increase
B. Decrease
C. Not be affected
D. Be infinity

Answer : B. Decrease
Explanation:-

7. In an UJT triggering circuit for SCR, pulses are generated at _________ of UJT

A. Emitter(E)
B. Base1(B1)
C. Base2(B2)
D. B1-B2

Answer : A. Emitter(E)
Explanation:-

8. In a half wave controlled rectifier feeding R-L load, the range of firing angle of thyristor is

A. 0≤α≤180°
B. 90≤α≤180°
C. 0≤α≤90°
D. 0≤α≤360°

Answer : A. 0≤α≤180°
Explanation:-

9. The DC output voltage, Vo of a basic chopper circit with input voltage, Vin and duty cycle δ is given by

A. V0=Vinxδ
B. Vo=Vin/δ
C. V0=Vin/(1-δ)
D. Vo=Vin

Answer : B. Vo=Vin/δ
Explanation:-

10. An AC regulator provides

A. Variable frequency, fixed magnitube AC
B. Fixed frequency, variable magnitude AC
C. Fixed frequency, fixed magnitude AC
D. Variable frequency, variable magnitude AC

Answer : C. Fixed frequency, fixed magnitude AC
Explanation:-