Question

Posted by FreshersWorld
7 Jan, 2012
Hello everyone, I gave the BHEL exam for ET on 31st Nov. my branch is Electronics. I assume you no the pattern, 240 questions, 150 mins, 120 non-technical, 60 technical, 60 General engineering.

Here are the questions i can recollect:

1) Why Mn is added in steel.

2) Purest form of iron.

3) Rail uses which type of steel.

4) Which of the metals is the poorest conductor of electricity(copper, silver etc.)

5) Laplace transform of a dirac delta function.

6) LVDT measures.

7) Enhancement mode occurs in which device(Jfet, bjt, mosfet, UJT)

8) Polyethene has what type of structure

9) Which of the materials is made of silica(glass, diamond)

10) Which of the materials has the least hardness(diamond,quartz,talc)

11) Which amplifier has more efficiency than class be amplifier

12) Space waves belong to which frequency range(vhf, uhf)

13) Permissible humidity in an air conditioned room

14) If S/N=43.25 db,no of levels

15) In radio receivers, Maximum image signal selectivity provided in which state-rf Amplifier, i-f amplifier, audio amplifier, frequency mixer.

16) One of the following cannot be used to demodulate ssb-product detector, diode balanced Modulator, bipolar transistor balanced modulator, complete phase shift generator.

17) Which of the following is not maxwell's equation-(a)b=uh (b)E=D/e (c)E=ed

18) VSWR

19) Sampling thereom is used in -fm, am, pcm

20) How many bits are used to address 64k memory location-3,10,16,32

21) Which of the foll flip flops is used as a latch-ttl, ecl, cmos, lsi

22) The sum s of a and b in a half adder can be implemented by using k nand gates. The value of k is -3,4,5,none of these

23) The most widely used bipolar technology for digital ic's is-dtl,ttl,ecl

24) Class be amplifiers has less efficiency compared to class A, class AB, class C, class A, AB and C

25) Which of the following is the most stable oscillator-wein bridge oscillator, hartley oscillator, colpitts oscillator.

26) In case of rc phase shift oscillator,the frequency of oscillations is given by-1/(2TT*6^1/2*RC),1/(2TTR*C^1/2,2TT/(RC)^1/2,2TT*(RC)^1/2

27) Barkhausen criterion for oscillator frequency is -AB=0,AB=1,AB=-1.

28) The standard if value for am receivers is-455khz, 455 mhz, 107 khz, 10.7 mhz

29) In a radio receiver the noise is generally increased by -mixer, local oscillator, power amplifier, power supply.

30) During the day time,ionosphere composes of -d, e, f2 layer; d, f1, f2 layer;d, e, f1, f2 layer.

31) When the modulating frequency is doubled,the modulation index is halved and the modulating voltage remains constant.the modulation system is-am,fm,pm,any one of them.

32) Octave frequency range is specified by - w2/w1=2,w2/w1=10,w2/w1=8.

33) The gain margin is the reciprocal of the gain at the frequency at which the phase becomes-0,90,180,270.

34) The foll system is generally preferred-overdamped, critically damped, underdamped, oscillatory.

33) The response of a control system having damping factor as unity will be Oscillatory, undamped, critically damped,none of the above.

34) The following compensator is used to increase the damping of a heavily under damped system-phase lag, phase lead, phase lag lead, none of these.

35) In the characteristic equation. 1+k/{s(s+1)(s+2)}=0,the centroid of the asymptotes is given by-1,-1,2,-2

36) Depth of modulation.

37) 3 zener diodes having the breakdown voltage 6 v in series, resultant voltage-6 V, 18 V.

38) Fermi level in ge-0.67, 1.2ev

39) Which of the following plot can be directly used to determine B-Vce versus Ic for constant Ib, Vbe versus Ib for constant Vce,Vcb versus Ic for constant Ie.

40) A DVM measures-peak value,r.m.s. value,peak to peak value,average value.

41) An ideal current controlled voltage source
has-Ri=infinite,Ro=infinite;Ri=0,Ro=infinite;Ri=0,Ro=0;Ri=infinite,Ro=0.

42) Rotameter used to measure-flow,rotations

43) Different between true value and indicated value-static error, dynamic error, absolute error

44) No.of 2:1 mux needed for 4:1 mux-2,3,4.

45) Red+green-black, violet.

46) Superconductivity means conductivity-infinite, 0.

47) Frequency of TE11 wave.

48) Process is irreversible if efficiency->50%,<50%.

Folks, these were the important questions i could recollect from the exam, i've skipped the non-technical part because that was pretty straight forward. Hope it is useful for future BHEL aspirants and hope i don't need this to come to my aid in the future.

BHEL Placement Paper Candidate Experiences Kolkata-31 Oct 2010