EKT Electrical & Electronics Sample Questions for AFCAT Exam

Instructions for Candidates

Time Allotted: 30 Minutes

1. Total number of Questions 50. Each Question is of three marks.

2. One mark will be deducted for every wrong answer.

3. Do not write or mark on Question Paper.

4. Question Paper to be returned before leaving the Exam Hall.

Q1. If sin x+(sin x)^{2} =1, then

(a) cos x+(cos x)^{2} =1

(b) cos x – (cos x)^{2} =1

(c) (cos x)^{2} – (cos x) =1

(d) (cos x)^{2} + (cos x)^{4} =1

Q2. Each edge of a cube is increased by 50%. The percentage increase in the surface area is (a) 50 (b) 125 (c) 150 (d) 300

Q3. The value of log 4 + log 5 – log 2 is (a) 1 (b) 7 (c) 10 (d) 9/2

Q4. The probability of drawing an ace or a spade or both from a deck of cards is (a) 4/52 (b) 13/52 (c) 1/52 (d) 16/52

Q5. Let θ be the angle between two vectors a and b, then cos θ is equal to (a) mod a + mod b (b) (a )+ mod b (c) mod (a+b) (d) ab/[ mod a x mod b]

Q6. Pressure is (a) scalar (b) vector (c) pseudo vector (d) Poynting vector

Q7. The force of attraction or repulsion between charges follows (a) square law (b) inverse square law (c) both (a) and (b) (d) none of (a) and (b)

Q8. The force experienced by a conductor of length L carrying current I placed parallel to the magnetic field of flux density B is (a) BIL (b) Zero (c) HIL (d) IL/B

Q9. A wave undergoes reflection from a rigid boundary. One of its characteristic parameters that changes is (a) frequency (b) phase (c) velocity (d) wavelength

Q10. The half-life period of a radioactive element is 140 days . After 560 days one gram of the element will reduce to (a) 1/2 g (b) 1/4 g (c) 1/8 g (d) 1/16 g

Q11. Which projection shows the object from angles in which the scales along each axis of object are equal (a) auxiliary projection (b) isometric projection (c) orthographic projection (d) objective projection

Q12. A charge of 2 coulombs every 0.5 sec signifies (a) 4 A of current (b) 1A of current (c) 2A of current (d) none of these

Q13. Transformer is a device used for (a) converting AC to DC (b) for stepping down AC Voltages (c) both stepping up/down AC Voltages (d) only stepping up AC Voltages

Q14. In order to get back the original signal from sampled signal , It is necessary to use (a) low pass filter (b) high pass filter (c) band pass filter (d) band reject filter

Q15. Superposition theorem can be applied only to circuits having elements (a) non-linear (b) passive (c) linear bilateral (d) resistive

Q16. Negative feedback reduces———in amplifiers (a) signal (b) amplification (c) distortion (d) none of the above

Q17. Whenever the two inputs are same the output is high for (a) EX-OR (b) EX-NOR (c) NOR (d) NAND

Q18. In digital Electronics a nibble is a collection of (a) 4 bits (b) 2 bits (c) 8 bits (d) 10 bits

Q19. If both R=1 and S=1 in RS Flip Flop then Q is (a) last value (b) set (c) reset (d) forbidden

Q20. Ideal OP Amp’s input resistance Is (a) zero (b) 100 k ohms (c) Infinite (d) 15 k ohm

Q21. A hard disk is divided into tracks which are further subdivided into (a) clusters (b) sectors (c) vectors (d) heads

Q22. Pentavalent impurities gives rise to more number of (a) electrons in valence band (b) electrons in conduction band (c) holes in valence band (d) holes in conduction band

Q23. A Varactor diode may be advantageous at microwave frequencies (a) for electronic tuning (b) as an oscillator (c) as a parametric amplifier (d) for frequency multiplication

Q24. When used in a circuit , a zener diode is always (a) forward biased (b) connected in series (c) troubled by overheating (d) reverse biased

Q25. The output from a laser is monochromatic , this means that it is (a) infrared (b) polarised (c) narrow beam (d) single frequency

Q26. In pneumatic control system, compensation is provided by (a) bimetallic strip (b) extension tube (c) restriction volume tube (d) none of the above

Q27. The main drawback of a feedback system is (a) large time delay (b) inefficiency (c) inaccuracy (d) unreliability

Q28. In an open loop control system (a) control action is independent of the output (b) control action depends upon human judgment (c) internal system changes are automatically taken care of (d) both (a) and (b)

Q29. Which of the following cannot be used to measure temperature (a) thermocouple (b) thermistor (c) pyrometer (d) thyristor

Q30. Poles are the complex frequencies of a transfer function where the response becomes (a) infinite (b) zero (c) oscillatory (d) decaying

Q31. The impulse response of an R-L circuit is a (a) rising exponential function (b) decaying exponential function (c) step function (d) parabolic function

Q32. The conversion of a signal representation from time domain to frequency domain is given by (a) Fourier transform (b) Shannon transform (c) inverse Fourier transform (d) inverse Laplace transform

Q33. The sampling theorem states that for a band limited signal of max frequency component fm (a) fs>=2fm (b) fs<=2fm (c) fs<=2fm (d) fs=fm

Q34. Voice signal frequency may lie anywhere between (a) 0 to 20 KHz (b) 0 to 1 MHz (c) 15 Hz to 15 KHz (d) none of these

Q35. Higher beamwidth of antenna implies (a) higher directivity (b) lesser directivity (c) higher bandwidth (d) lower bandwidth

Q36. PWM signal can be generated by (a) a monostable multivibrator (b) an astable multivibrator (c) integrating PPM signal (d) differentiating PPM signal

Q37. In broadcast receiver most of the selectivity is achieved in (a) IF section (b) RF section (c) audio stage (d) mixer

Q38. The IF bandwidth of a radar receiver is inversely proportional to the (a) pulse width (b) PRF (c) pulse Interval (d) square root of peak transmitted power

Q39. Quantizing noise occurs in (a) TDM (b) FDM (c) PCM (d) PWM

Q40. In order to separate channels in a FDM receiver it is necessary to use (a) AND gates (b) OR gates (c) integration (d) band pass filter

Q41. The physical layer, in reference to the OSI model, defines (a) data link procedures that provide for the exchange of data via frames that can be sent and received (b) the interface between the X.25 network and packet mode device (c) the virtual circuit interface to packet-switched service (d) all of the above

Q42. Which of the following device copies electrical signals from one Ethernet to another? (a) bridge (b) repeater (c) hub (d) passive hub

Q43. Which of the following TCP/IP protocol is used for transferring files from one machine to another? (a) RARP (b) ARP (c) TCP (d) FTP

Q44. What does the acronym ISDN stand for? (a) Indian Standard Digital Network (b) Integrated Services Digital Network (c) Intelligent Services Digital Network (d) Integrated Services Data Network

Q45. The following is measure of reproducibility in a measurement (a) resolution (b) drift (c) precision (d) fidelity

Q46. What part of the transformer is subjected to maximum heating (a) core (b) winding (c) oil (d) frame

Q47. The servo motor differs from ordinary motor in that it has (a) low inertia & high torque (b) high inertia & high torque (c) low inertia & low torque (d) high inertia & low torque

Q48. The speed of DC motor is (a) always constant (b) directly proportional to back emf (c) directly proportional to flux (d) inversely proportional to the product of back emf and flux

Q49. Which of the following DC generator cannot build up in an open circuit (a) shunt (b) series (c) short shunt (d) long shunt

Q50. The armature circuit resistance of DC generator is closest to (a) 1 ohms (b) 4π ohms (c) 1000 ohms (d) 20,000 ohms

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