BSNL –JTO SAMPLE PAPER

BSNL –JTO SAMPLE PAPER-1
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1. Of the following bridges the one which can be used for the measurement of dielectric loss of a capacitor is –
a.) Schering bridge
b) Heaviside campbell equal ratio voltage
c) Owen bridge
d) Anderson bridge

2. LVDT is uses as a –
a). Displacement transducer
b) Pressure transducer
c) Temperature
d.) Any of the above

3. Polarization is a measure of -
a.) Dielectric constant per unit volume.
b.)Voltage gradient to produce electrical breakdown
c.) Product of charge and distance
d.)Excess charge density

4. Compared to the inductive type of transducer, capacitive transducer is superior for the measurement of displacement because of -
a.)Absence of non-linearity
b.) High frequency response
c.) Small size
d.) High accuracy

5. An incremental model of a solid state device is one which represents the –
a.) ac property of the device at the desired operating point
b) dc property of the device at all operating points
c) Complete ac and dc behaviour of the device at all operating points
d)ac property of the device at all operating points.

6. The ac resistance of a forward biased p-n junction diode operating at a bias voltage 'V' and carrying current 'I' is –
a ) Zero
b) a constant value independent of Vand I
c) very high
d.) none of the above

7. A meter is shielded with a soft iron to –
a) Prevent damage from rough use
b) Keep moisture out of movement
c) Protect meter movement from stray magnetic fields
d) Achieve all of the above

8. A capacitor that has been connected across a battery for comparatively long time becomes–
a) Charged
b) Discharged
c) Short - circuited
d) Defective

9. The charge on the plates of a capacitor is given by the expression –
a.) Q = VI
b.) Q = IR
c.) Q = CV
d.) Q = IC

10. Silicon steel used for electrical purposes has silicon percentage of –
a.) 0.5
b.) 2.5
c.) 3.4
d). None

11. The feature of VTM is its –
a.) Low input impedance
b.) Low power consumbtion
c.) The ability to measure wider ranges of voltage and resistances
d) None

12. In an N-type semiconductor, the position of the fermi level –
a.) Is lower than the centre of the energy gap
b.) Is at the centre of the energy gap
c.) Is higher than the centre of the energy gap
d.) Can be anywhere depending upon the doping concentration

13. A JFET can operate in –
a.) depletion and enhancement model
b.) depletion mode only
c.) enhancement mode only
d.) neither enhancement nor depletion mode

14. Consider the following semiconductor diodes –
a.) Germanium diode
b.) Silicon diode
c.) Tunnel diode
d.) Schottky diode

15. A diode with a PIV of 50V is likely to break down when rectifying 50v ac supply because –
a.) it is made of defective material
b.) it is incorrectly connected to the supply
c.) peak value of ac supply exceeds the PIV value
d.) ac supply is of extremely high frequency.

16. The set of transistor characteristics that enables a to be determined directly from the slope is –
a.) CE transfer characteristics
b.) CE output characteristics
c.) CB transfer characteristics
d.) CB input characteristics

17. For an N-channel JFET, the drain voltage has to be –
a.) positive with respect to the source
b.) negative with respect to the source
c.) uncharged with respect to the source
d.) none

18. The SCR is often employed as a –
a.) Source-controlled switch
b.) Drain-controlled switch
c.) Gate-controlled switch
d ) None

19. An oscilloscope has an input impedance consisting of 1MW and 20pF in parallel. A high impedance probe connected to the input of this oscilloscope has a 10MW series resistance, this 10MW resistance –
a.) Need not be shunted
b.) Should be shunted by a 2pF capacitor
c.) Should be shunted by a 20pF capacitor
d.) Should be shunted by a 200pF capacitor

20. Compared to silicon, gallium arsenide (GaAs) has –
a.) Easier to grow crystals since the vapour- pressure of arsenic is high
b.) Higher optoelectronic conversion efficiency
c.) Both a and b
d). None

21. When the network shown in the fig draw a current I and if the ends ab are shorted, the current drawn would be –
a.) I
b.) I\ 4
c.) 4 I
d.) 2 I

22. When all the resistances in the circuit are of one ohm each, then the equivalent resistance across the points A and B will be –
a.) 1W
b.) 0.5W
c.) 2W
d )1.5W

23. Of the following periodic waveforms the one having only odd harmonics of sinusoidal waveform is-
a.) 1 and 2
b.) 1 and 3
c.) 1 and 4
d.) 2 and 4

24. When in the network shown in the given fig, the switch K is dosed at t = 0 with the capacitor uncharged then the value for at t = 0+ will be –
a.) 100 amp./sec.
b.) –100 amp./sec.
c.) 1000 amp./sec.
d.) –1000 amp./sec.

25. For the circuit shown in the given figure, the voltage VAB is –
a.) 6V
b.) 10V
c.) 25V
d.) 40V

26. In the network shown in the given fig. current i = 0 when E = 4V, I = 2A and I = 1A when E = 8V, I = 2A. The Thevenin voltage and the resistance into the terminals AB are –
a.) 4V, 2W
b.) 4V, 4W
c.) 8V, 2W
d.) 8V, 4W

27. The effective resistance between the terminals A and B in the circuit shown in the fig. is –
R
a.) R
b.) R-1
c.) R/2
d.) 6/11 R

28. When in a two terminal network, the open circuit voltage measured at the given terminals by an electronic voltmeter is 100V and a short circuit current measured at the same terminals by an ammeter of negligible resistance is 5A then if a resistor of 80W is connected at the same terminal, then the current in the load resistor will be –
a. 1A
b.) 1.25A
c). 6A
d. 6.25A

29. The electric potential due to an electric dipole of length L at point distance r away from it will be doubled if the -
a.) Length L of the dipole is doubled
b ) r is doubled
c) r is halved
d ) L is halved

30. When a particular mode is excited in a waveguide there appears an extra electric component in the direction of propagation . The resulting mode is
a. ) Longitudinal electric
b. ) Transverse electromagnetic
c. ) Transverse magnetic
d ). Transverse electric

31. When for a transmission line the open circuit and short circuit impedance are 20W and 5 W respectively then the characteristic impedance of the line is -
a. ) 100 Ohms
b ). 50 Ohms
c. ) 25 Ohms
d. ) 10 Ohms

32. In an ideal transmission line with matched load, the voltage standing wave ratio and reflection coefficient are respectively -
a. ) 1 and 1
b ). infinity and 1
c ) infinity and 0
d.) 1 and 0

33. When an electric charge of 100 coulombs is enclosed in sphere of radius 100 m then the electric displacement density ( in coulomb / m2) D is –
a. ) 0.0833
b ). 0.833
c. ) 1.666
d. ) 10

34. For the dominant mode in a rectangular wavelength with breadth 10 cm, the guide wavelength for a signal of 2.5 GHz will be -
a. ) 12 cm
b. ) 15 cm
c. ) 18 cm
d. ) 20 cm

35. When the phase velocity of an electromagnetic waves depends on frequency in any medium, the phenomenon is called-
a. ) Scattering
b. ) Polarization
c. ) Absorption
d. ) Dispersion

36.Antennas commonly used for microwave links are -
a. ) Loop antenna
b. ) Log-periodic antennas
c. ) Paraboloidal dishes
d ). Rhombic antennas

37. One of the following instrument which may be used to measure the optical activity of compounds is –
a. ) Infrared spectrometer
b. ) Atomic absorption spectrometer
c. ) Polarimeter
d. ) Flouroscope

38. Schering bridge measures –
a. ) Capacitance dielectric loss
b. ) Inductance
c. ) Resistance
d. ) Mutual inductance

39. When a square wave is fed to an RC circuit, then –
a. ) voltage across R is square and across C is not square
b. ) voltage across C is not square and across R is not square
c. ) voltage across both R and C are square
d. ) voltage across both R and C are not square

40. The time constant of the RC circuit is –
a. ) less than the time period of the input square wave.
b ). much larger than the time period of the input square wave.
c.) equal to the time period of the input square wave.
d ). none

41. Harmonic distortion for each frequency can be obtained by harmonic analyser of the –
a. ) heterodyne type
b. ) tuned circuit type
c. ) fundamental suppression type`
d. ) bridge circuit type.

42. A three phase wattmeter requires –
a ). only two current coils and two pressure coils
b.) only one current coil and two pressure coil
c. ) only two current coils and one pressure coil
d. ) only current coil

43. A low pass filter circuit is basically –
a. ) a differentiating circuit with low time constant
b. ) a differentiating circuit with large time constant.
c. ) an integrating circuit with low time constant.
d. ) an integrating circuit with large time constant.

44. If the differential pressure in restriction type flow measuring devices is then the flow will be proportional to –

45. When a system is represented by the transfer function then the dc gain of this system is –
a.) 1
b.) 2
c.) 5
d.) 10

46. Silicon based semiconductor device called thyristor was first fabricated by –
a). Jell laboratories in U.S.A
b). Maxwell laboratories in U.S.A
c.) Bell laboratories in U.S.A
d). GEC laboratories in U.S.A

47. A semiconductor based temperature transducer has a temperature coefficient of –2500mV/0C. This transducer is indeed a –
a.) Thermistor
b.) Forward biased pn junction diode
c.)Reverse biased pn junction diode
d.) FET

49. Which of the followings pairs of Telemetry situations and Modulation techniques and conditions is correctly matched-
a.) Pulse amplitude modulation Low amplitude signals
b.) Pulse position modulation For short distance when power is enough
c.) Pulse width modulation Power to be spent in telemetry is required to be low
d.) Pulse code modulation, minimization of interference effects.

50. The SCR ratings di/dt in A/m sec and dv/dt in n/m sec, may vary, respectively between-
a.) 20 to 500, 10 to 100
b.) both 20 to 500
c.) both 10 to 100
d.) 50 to 300, 20 to 500