Quiz: Electrical Engineering 21 May 2020

Quiz: Electrical Engineering
Exam: UPPSC AE
Topic: Analog and digital electronics (electrical engineering)

Each question carries 1 mark.
Negative marking: 1/4 mark
Time: 10 Minute

Q1. A FET transistor with an antiparallel body diode block:
(a) Bidirectional voltage and passes unidirectional current
(b) Bidirectional voltage and passes bidirectional current
(c) Unidirectional voltage and passes unidirectional current
(d) Unidirectional voltage and passes bidirectional current

 

Q2. Turn-on of a Thyristor takes place when
(a) anode to cathode voltage is positive
(b) anode to cathode voltage is negative
(c) there is a positive current pulse at the gate
(d) the anode to cathode voltage is positive and there is a positive current pulse at the gate

 

Q3. After firing an SCR, the gate pulse is removed. The current in the SCR will
(a) remain the same
(b) immediately fall to zero
(c) rise up
(d) rise a little and then fall to zero

 

Q4. When a thyristor is in ON state, its gate drive be
(a) removed to save power
(b) removed or may not be removed
(c) not removed as it will turn off the thyristor
(d) removed to avoid increased losses and higher junction temperature

 

Q5. Current in SCR to turn on transient can be reduced by
(a) connecting a small inductor in series with the anode
(b) connecting a small inductor in parallel with the anode
(c) connecting a small capacitor in series with the anode
(d) connecting a small capacitor in parallel with the anode

 

Q6. Which of following does not cause damage of an SCR?
(a) high current
(b) high rate of rise of current
(c) high temperature rise
(d) high rate of rise of voltage

 

Q7. When compared to those of a symmetrical thyristor, the turn off time and reverse blocking voltage of an asymmetrical thyristor are respectively
(a) large and large
(b) large and small
(c) small and large
(d)small and small

 

Q8. The duration of reverse recovery transient affects the following aspect in a power diode
(a) peak inverse voltage
(b) forward threshold voltage
(c) speed of response
(d) average current

 

Q9. Surge current rating of an SCR specifies the maximum
(a) repetitive current with rectangular wave
(b) non- repetitive current with sine wave
(c) non- repetitive current with rectangular wave
(d) repetitive current with sine wave

 

Q10. The dv/dt effect in SCR can result in
(a) Low capacitive charging current
(b) false triggering
(c) increased junction capacitance
(d) high rate of rise of anode voltage

 

Solutions
S1. Ans. (d)
Sol. Unidirectional voltage and passes bidirectional current

 

S2. Ans. (d)
Sol. the anode to cathode voltage is positive and there is a positive current pulse at the gate.

 

S3. Ans. (a)
Sol. remain the same

 

S4. Ans. (d)
Sol. removed to avoid increased losses and higher junction temperature

 

S5. Ans. (a)
Sol. connecting a small inductor in series with the anode

 

S6. Ans. (d)
Sol. high rate of rise of voltage

 

S7. Ans. (d)
Sol. Both quantities need to be small.

 

S8. Ans. (a)
Sol. The duration of reverse recovery transient affects the following aspect in a power diode peak inverse voltage.

 

S9. Ans. (b)
Sol. non- repetitive current with sine wave

 

S10. Ans. (b)
Sol. false triggering

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