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question bank for bsnl jto |
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Re: question bank for bsnl jto
Ok, I am providing you the previous year question paper of BSNL Junior Telecom Officers JTO Exam BSNL JTO exam question paper 1. One of the following statement which is true for relative dielectric constant is - a) It is dimensionless b) It is not equal to unity for vacuum c) It's value for all substances is less than one d) None Answer is :- It is dimensionless 2. Pure metals generally have- a) high conductivity and low temperature coefficient b) high conductivity and large temperature coefficient c) low conductivity and zero temperature coefficient d) low conductivity and high temperature coefficient Answer is :- high conductivity and large temperature coefficient 3. For small size, high frequency coils, the most common core material is a) Air b) Ferrite c) Powdered ion d) Steel Answer is :- Air 4. For an abrupt junction Varactor diode, the dependence of device capacitance (C) on applied reverse bias (V) is given by- a) C a V1/3 b) C a V-1/3 c) C a V1/2 d) C a V-1/2 Answer is :- C a V-1/3 5. A superconductor is a- a) A material showing perfect conductivity and Meissner effect below a critical temperature b) A conductor having zero resistance c) A perfect conductor with highest dimagnetic susceptibility d) A perfect conductor which becomes resistive when the current density through it exceeds a critical valueAnswer is :-A material showing perfect conductivity and Meissner effect below a critical temperature 6. When a semiconductor based temperature transducer has a temperature coefficient of " 2500 mV/0C then this transducer is indeed a- a) Thermistor b) Forward biased pn junction diode c) Reverse biased pn junction diode d) FET Answer is :- Forward biased pn junction diode 7. The location of lightning arrestor is - a) Near the transformer b) Near the circuit breaker c) Away from the transformer d) None Answer is :- Near the transformer 8. Time constant of an RC circuit increases if the value of the resistance is - a) Increased b) Decreased c) Neither a nor b d) Both a and b Answer is :- Increased 9. Intrinsic semiconductors are those which - a) Are available locally b) Are made of the semiconductor material in its purest from c) Have more electrons than holes d) Have zero energy gaps Answer is :- Are made of the semiconductor material in its purest from 10. The primary control on drain current in a JFET is exerted by - a) Channel resistance b) Size of depletion regions c) Voltage drop across channel d) Gate reverse bias Answer is :- Gate reverse bias 11. The electrical conductivity of metals which is expressed in ohm-1 m-1 is of the order of - a) 1010 b) 105 c) 10-4 d) 10-6 Answer is :- 105 12. When biased correctly, a zener diode " a) acts as a fixed resistance b) has a constant voltage across it c) has a constant current passing through it d) never overheats Answer is :- has a constant voltage across it 13. The current amplification factor adc is given by " a) IC/IE b) IC/IB c) IB/IC d) IB/IC Answer is :- IC/IE 14. Compared to bipolars, FETs have- a) high input impedance b) low input impedance c) same input impedance d) none Answer is :- high input impedance 15. The source-drain channel of JFET is - a) ohmic b) bilateral c) unilateral d) both a and b Answer is :- both a and b 16. diac is equivalent to a - a) Pair of SCRs b) Pair of four layer SCRs c) Diode and two resistors d) Triac width Answer is :- Pair of four layer SCRs 17. When a sample of N type semiconductor has electron density of 6.25 ´ 1011 /cm3 at 300K and if the intrinsic concentration of carriers in this sample is 2.5 ´ 1013/cm3 then the hole density will be " a) 106/cm3 b) 103/ cm3 c) 1010/ cm3 d) 1012/ cm3 Answer is :- 103/ cm3 18. The statement 'In any network of linear impedances, the current flowing at any point is equal to the algebraic sum of the currents caused to flow at that point by each of the sources of emf taken separately with all other emf's reduced to zero' represents - a) Kirchhoff's law b) Norton's theorem c) Thevenin's theorem d) Superposition theorem Answer is :- Superposition theorem 19. One of the following modes which has the characteristics of attenuation becoming less as the frequency is increased and is attractive at icrowave frequencies of circular cylindrical wave guides is " a) TE1 mode b) TM01 mode c) TE01 mode d) Higher order mode Answer is :- TE01 mode 20. A two-port network is symmetrical if " a) z11z22 " z12z21 = 1 b) h11h22 " h12h21 = 1 c) AD " BC = 1 d) y11y22 " y12y21 = 1 Answer is :-AD " BC = 1 21. For transmission line load matching over a range of frequencies, it is best to use a- a) balun b) broad band directional coupler c) double stub d) single stub of adjustable position Answer is :- double stub 22. The poles and zeros of a driving point function of a network are simple and interlace on the negative real axis with a pole closest to the origin. It can be realised - a) by an LC network b) as an RC driving point impedance c) as an RC driving point admittance d) only by an RLC network Answer is:- only by an RLC network 23. Poles and zeros of a driving point function of a network are simple and interlace on the jw axis. The network consists of elements " a) R and C b) L and C c) R and L d) R, L and C Answer is :- L and C 24. For a two port reciprocal network, the output open circuit voltage divided by the input current is equal to " a) B b) Z12 c) " d) h12 Answer is :- Z12 25. In a short electric doublet the radiation properties are so that- a) The induction field diminishes as the square root of the distance and is only appreciable in the vicinity of the conductor. b) In the radiation, magnetic field is minimum when the current is maximum. c) The radiation resistance of a short doublet antenna is extremely high. d) Mean rate of power through a unit area of spherical sphere surrounding this doublet is proportional to the square of the elemental length, other factors remaining constant. Answer is :-Mean rate of power through a unit area of spherical sphere surrounding this doublet is proportional to the square of the elemental length, other factors remaining constant. 26. The frequency modulated (FM) radio frequency range is nearly - a) 250 "300 MHz b) 150 " 200 MHz c) 90 " 105 MHz d) 30-70 MHz Answer is :-90 " 105 MHz 27. In an underground cable the distortion in the transmission of carrier frequency can be eliminated by using - a) Inductive loading b) Resistive loading c) Capacitive loading d) Shielding Answer is :- Inductive loading 28. The characteristic impedance of a transmission line with inductance 0.294 mH /m and capacitance 60 pF/m is - a) 49 W b) 60 W c) 70 W d) 140 W Answer is :- 70 W 30. For a quarter wavelength ideal transmission line of characteristic impedance 50 ohms and load impedance 100 ohms, the input impedance will be " a) 25W b) 50Wc) 100W d) 150W Answer is :- 25W 31. The depth of penetration or skin depth for an electromagnetic field of frequency 'f' in a conductor of resistivity r and permeability m is- a) inversely proportional to r and f and directly proportional to m b) directly proportional to r and inversely proportional to f and m c) directly proportional to f and inversely proportional to r and m d) inversely proportional to r and m and directly proportional to f Answer is :- directly proportional to r and inversely proportional to f and m 32. When an antenna has a gain of 44dB then assuming that the main beam of the antenna is circular in cross-section the beam width will be - a) 0.4456 0 b) 1.44560 c) 2.44560 d) 3.44560 Answer is :- 2.44560 33. Lens antennas used for microwaves are usually made of - a) Polystyrene b) Glass of low refractive index c) Paraboloid surfaces d) Dielectric media having large refractive index An, 34. One of the following types of instrument which is an electrometer is - a) Electrodynamometer b) PMMC c) Electrostatic d) Moving iron Answer is :- Electrostatic 35. When an ac current of 5A and dc current of 5A flow simultaneously through a circuit then which of the following statement is true ? a) An ac ammeter will read less than 10A but more than 5A b) An ac ammeter will read only 5A c) A dc ammeter will read 10A d) A dc ammeter will read zero Answer is :- An ac ammeter will read less than 10A but more than 5A 36. When Q factor of a circuit is high, then - a) power factor of the circuit is high b) impedance of the circuit is high c) bandwidth is larged) none of these Answer is :- none of these 37. The resolution of a logic analyser is - a) the maximum number of input channels b) the minimum duration of the glitch it can capture c) it's internal clock period d) the minimum amplitude of input signal it can display Answer is :- the minimum amplitude of input signal it can display 38. A memoryless system is " a) causal b) not causal c) nothing can be said d) none Answer is :- causal 39. An air capacitor is a " a) time variant b) active device c) time invariant d) time invariant and passive device Answer is :-time invariant and passive device 40. Thermistors are made of - a) pure metals b) pure insulators c) sintered mixtures of metallic oxides d) pure semiconductor Answer is :- sintered mixtures of metallic oxides |
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