Company: Air India

AIR INDIA Electronics and Telecommunication Aptitude – I Material, Components and Devices – Multiple Choice Questions

1 Make the false statement out of the following

A) Phosphorous has 5 valence electron (B) Hole current is the movement of positive charges in the opposite direction from electron flow(C) The internal barrier potential at PN junctions for silicon is approximately 1.1 eV (D) None of these.

2. All the materials with a basic unit, which has a center of symmetry i.e. starting from the center and drawing a vector to one of the surrounding ions, one finds a similar ion at a position. Corresponding to a vector of equal length drawn in the opposite direction, are known as
(A) Magneto striction (B) Piezoelectric (C) Electrostriction (D) None of these

3 . The relative permeability of diamagnetic material is of the order of
(A) 1+ 10-5 (B) 10-5 (C) 1-10-5 (D) 105

4 .The ferromagnetic curies temperature in degrees absolute for iron is
(A) 990 (B) 1428 (C) 631 (D)1043

5 .Which of the following material is used for making permanent magnets

(A) Alnico V (B) Carbon Steel (C) Plantinum cobalt (D) All of these

6 .If a number of domains are arranged such that no poles exists at the surface and no lines of force go out of the material the magnetostatic energy of a ferromagnetic material
(A) reduces (B) remains the same (C) increases (D) it may increase or decrease

7 .On the application of an electric field, a polarisation process occurs as a function of time. the polarisation p (t) as a functionof time t is given by
(A) P (t) = P/[exp(-t/tr) + 1] (B) P (t) = P/[1-exp(-t/tr)] (C) P (t) = P[1-exp(-t/tr)] (D) None of these

8 . A constant voltage generator has
(A) low internal resistance (B) minimum efficiency (C) high internal resistance (D) minimum current capacity

9 . which of the following is a low pass filter ?
(A) L type with series C and shunt L (B) T type with series L and shunt C (C) T type with series C and shunt L (D) L type with series L and shunt C

10 .With an indirectly heated cathode the heater voltage
(A) must be a steady d.c. voltage (B) is separate from the cathode circuit (C) is applied to the cathode (D) is equal to the c-bias voltage

11 .Which is single 8-input NAND gate ?
(A) SN 7430 (B) SN 7432 (C) SN 7440 (D) SN 7410

12 EZ-80 in radio is a
(A) full wave rectifier (B) audio amplifier (C) line output pentode (D) None of these

13 .In LED, light is emitted because
(A) We make the light fall on LED (B) recombination of charges takes place (C) diode emits light when heated (D) None of these

14 .which of the following has the highest voltage gain ?
(A) CB (B) CE (C) CC (D) None of these

15 i)Transistors on a monolithic linear IC unit are generally PNP on a silicon substrate (ii) typical values of L integrated on a chip are 10 to 100 mH. Indicate correct combination
(A) F, F (B) T, F (C) F, T (D) T, T

16 Bridge rectifiers are preferred because
(A) less peak inverse voltage (B) they require small transformer (C) Both (A) & (B) (D) None of these

17 .Triac is a
(A) 2 terminal unilateral switch. (B) 3 terminal bidirectional switch (C) 2 terminal bidirectional switch (D) 3 terminal unilateral switch

18 . SCS is a device which is
(A) physically smaller than SCR and operates at lower current and voltage (B) physically larger(C) physically smaller but operates at high current and voltage as compared to SCR. (D) physically larger and operate at high voltage and current

19 .Thyristor can be turned off
(A) by reversing the anode voltage (B) by reducing the anode current below holding current value (C) Both (A) & (B) (D) None of these

20 .SN 7410 IC is a
(A) triple 3 input Nand gate (B) triple 3 input Nand with open collector (C) 2- input Nand gate (D) None of these

21 . h22 hybrid parameter is
(A) out put conductance with input open circuited (B) input resistance with output open circuited(C) output resistance with input open circuited (D) input conductance with output open circuited.

22 .Cascade configuration is
(A) CE- CC (B) CE- CE (C) CE-CB (D) CE- CE

23 .Class B and Class C operations are used in (respectively)
(A) tunned amblifiers (B) untunned and tunned amblifiers (C) tunned and untunned amblifiers (D) untunned amblifiers

24 . In Voltage series negative feedback Ri and Rof
(A) increases, decreases as compared to previous value (B) increases, increases (C) decreases, increases (D) decreases, decreases

25 .Pushpull amplifier result in
(A) less distortion and more output power (B) less distortion, less output power (C) more distortion , more output power (D) more distortion , less output power

26 .Class B push pull amblifier suffers from
(A) cross over distortion (B) inter modulation distortion (C) excessive harmonic distortion (D) None of these

27 . In trans- resistance amplifiers(A) O/P current depends on input voltage. (B) O/P voltage depends on input current (C) O/P voltage depends on input voltage. (D) O/P current depends on input current.

28 . With negative feed back, the Rof (output) and Rif (input) impedance in case of voltage series feedback amblifier, respectively
(A) increases, increases (B) decreases, decreases (C) increases, decreases (D) decreases, increases

29 . Emitter follower is characterised by
(A) low output impedance and little distortion (B) low output impedance and more distortion(C) more output impedance and more distortion (D) None of these

30 .The effect of bypass capacitor in amplifier design is adversely seen on
(A) low frequency response (B) medium frequency response (C) high frequency response (D) None of these

31 . if the input resistance is reduced in tube amplifier then the power gain of the driving amplifier for moderate feedback, and the voltage gain respectively (A) increases, decreases (B) both increases (C) both decreases (D) remain same

32 .Conversion efficiency for class A and B respectively are
(A) 25, 50% (B) 50, 50% (C) 50, 25% (D) 50, 78.4%

33 . cascade amplifiers are used in (A) tunned amplifier design (B) video amplifier (C) voltage amblifier (D) power amplifier

34 . The high frequency response of an amplifier can be determined from
(A) hybrid – T- model (B) h-parameter model of the amplifier (C) hybrid pie -model (D) None of these

35 .The dynamic impedance of a Zemer diode
(A) decreases with increase in current passing through it (B) increase with increase in current passing through it (C) is independent of current passing through it (D) None of these

36 . Ripple factor (r) of an inductance can be calculated from the formula
(A) r = 2410/LRL (B) r = RL/1600L (C) r = 1600L/RL (D) None of these

37 .The purpose of an amplifier is(A) to increase voltage and current of an input signal (B) to introduce distortion in the signal fed to it (C) to attenuate the single fed to its point (D) to increase voltage current or power of an input signal.

38 .The standard aircraft frequency is
(A) 60 Hz (B) 50 Hz (C) 400 Hz (D) None of these

39. Conversion efficiency for the amplifier is signal power delivered (A) n = to load / d.c power supplied to output circuit *100 (B) n = output power/input power *100 (C) n = output circuit / signal power delivered to load *100 (D) None of these