BSNL JTO Recruitment Test Paper Pattern Set 1

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

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

3. For small size, high frequency coils, the most common core material is
a) Air
b) Ferrite
c) Powdered ion
d) Steel

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

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 value

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

7. The location of lightning arrestor is –
a) Near the transformer
b) Near the circuit breaker
c) Away from the transformer
d) None

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

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

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

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

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

13. The current amplification factor adc is given by –
a) IC/IE
b) IC/IB
c) IB/IC
d) IB/IC

14. Compared to bipolars, FETs have-
a) high input impedance
b) low input impedance
c) same input impedance
d) none

15. The source-drain channel of JFET is –
a) ohmic
b) bilateral
c) unilateral
d) 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

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

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

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

20. A two-port network is symmetrical if –
a) z11z22 – z12z21 = 1
b) h11h22 – h12h21 = 1
c) AD – BC = 1
d) y11y22 – y12y21 = 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

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

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

24. For a two port reciprocal network, the output open circuit voltage divided by the input current is equal to –
a) B
b) Z12
d) h12
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.

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

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

28. The charachteristic impendance 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

29. One of the following statements which is not true for a strip line compared to a waveguide is –
a) It can be directly connected to semiconductor microwave devices
b) It is much smaller in size
c) It has a smaller bandwidth
d) Losses are less