Multiple Choice Questions on Basic Electrical Engineering

21-BY 127 is a:
(A) PNP transistor
(B) NPN transistor
(C) TRIAC
(D) Semi conductor diode
22-Resultant flux of 3 phase induction motor is:
(A) (√3/2)φm
(B) (3/2)φm
(C) 3 φm
(D) 2 φm
23-Which has negative temperature coefficient resistance?
(A) Copper
(B) Aluminium
(C) Iron
(D) Carbon
24-Syncronous speed of a 3 phase, 4 pole, 50Hz induction motor is
(A) 1500 rpm
(B) 1440 rpm
(C) 3000 rpm
(D) 2880 rpm
25-Maximum number of electrons in valence shell of an atom is:
(A) 3
(B) 6
(C) 8
(D) 16
26-The following is Y class insulating material:
(A) Mica
(B) Cotton
(C) Porcelain
(D) Asbestos
27-Electric charge is equal to:
(A) It
(B) I/t
(C) I²t
(D) I²/t
28-Resonant frequency of an ac series circuit is:
(A) 1/2π(LC)^1/2
(B) 1/4π(LC)^1/2
(C) 1/4πLC
(D) 1/2πLC
29-1N 4007 is semi conductor diode. Here 1N represents:
(A) Forward current
(B) Voltage drop
(C) One layer
(D) One PN junction
30-Limiting temperature of F class insulating material:
(A) 225°C
(B) 105°C
(C) 120°C
(D) 155°C
ANSWERS:
21-(D), 22-(B), 23-(D), 24-(A), 25-(C), 26-(B), 27-(), 28-(A), 29-(A), 30-(D)