Company: Hindustan Aeronautics Limited
[1] Which of the following statements are correct?
1. Thyristor is current driven device
2. GTO is current driven device
3. GTR is current driven device
4. SCR is a pulse triggered device
A.1 and 2
B.1, 2, 3
C.All
D.4 only
Ans:C
[2] Which of the following statements are correct?
GTO is a pulse triggered device
MOSFET is uni-polar device
SCR is a bipolar device
Continuous gate signal is not required to maintain the SCR to be in ON state
A. 1, 2, 4 only
B. 1, 2 only
C. 4 only
D. All
Ans: D
[3] Which of the following is not a fully controlled semiconductor device?
a. MOSFET
b. IGBT
c. IGCT
d. SCR
Ans: D . Only turn on of the SCR can be controlled whereas in other devices we can control both turn on and turn off
[4] Which of the following is not associated with p-n junction
A. junction capacitance
B. charge storage capacitance
C. depletion capacitance
D. channel length modulation
Ans: D
[5] In a p-n junction diode under reverse bias, the magnitude of electric field is maximum at
A. the edge of the depletion region on the p-side
B. the edge of the depletion region on the n-side
C. the p-n junction
D. the center of the depletion region on the n-side
Ans: C
[6] An n-channel JFET has IDSS=2mA, and Vp=-4V. Its transconductance gm=(in mA/V) for an applied gate to source voltage VGS=-2V is
A. 0.25
B. 0.5
C. 0.75
D. 1
Ans: B
[7]The MOSFET switch in its on-state may be considered equivalent to
A. resistor
B. inductor
C. capacitor
D. battery
Ans: C
[8] The effective channel length of a MOSFET in a saturation decreases with increase in
A. gate voltage
B. drain voltage
C. source voltage
D. body voltage
Ans:B
[9] The early effect in a bipolar junction transistor is caused by
A. Fast turn – on
B. Fast turn – off
C. Large collector – base reverse bias
D. Large emmiter – base forward bias
Ans: C
[10] MOSFET can be used as a
A. Current controlled capacitor
B. Voltage controlled capacitor
C. Current controlled inductor
D. Voltage controlled inductors
Ans: B
Transformers objective type questions
[1] The ordinary two winding transformer’s primary and secondary windings always have
A. different no of turns
B. same size of copper wire
C. a common magnetic circuit
D. separate magnetic circuits
Ans: C
[2] No load test on a transformer is carried out to find
A. copper loss
B. magnetising current
C. magnetising current and no load loss
D. efficiency of the transformer
Ans:C
[3] Transformers are rated in KVA instead of KW because
A. load power factor is often not known
B. KVA is fixed whereas KW depends on load power factor
C. Total transformer loss depends on volt ampere
D. It has become customary
Ans: C
[4] Transformer cores are laminated in order to
A. simplify its construction
B. minimise eddy current loss
C. reduce cost
D. reduce hysteresis loss
Ans: B
[5] A step up transformer increases
A. voltage
B. current
C. power
D. frequency
Ans: A
[6] In a two winding transformer, the primary and secondary induced emf E1 & E2 are always
A. equal in magnitude
B. anti phase with each other
C. in phase with each other
D. determined by load on transformer secondary
Ans:C
[7] In a transformer, the leakage flux of each winding is proportional to the current in that winding because
A. Ohm’s law applies to magnetic circuits
B. Leakage paths do no saturate
C. the two windings are electrically isolated
D. mutual flux is confined to the core
Ans: B
[8] In a two winding transformer, the emf /turn in secondary winding is always……the induced emf power turn in primary
A. equal to k times
B. equal to 1/k times
C. equal
D. greater than
Ans:C
[9] In transformer terminology, the ratio 20:1 indicates that
A. there are 20 turns on primary one turn on secondary
B. secondary voltage is 1/20th of the primary
C. primary current is 20 times greater than the secondary current
D. for every 20 turns on primary, there is one turn on secondary
Ans: B
[10] In performing the short circuit test of a transformer
A. high voltage is usually short circuited
B. low voltage side is usually short circuited
C. any side is short circuited with preference
D. none of the above
Ans: B