BSNL GE-JTO Recruitment Examination Test Paper - IV Reactive current through the inductive load produces- a) Magnetic field b) Electric field c) Super magnetic field d) None When a piece of copper and another of germanium are cooled from room temperature to 800 K then the resistance of - a) each of them increases b) each of them decreases c) copper increases and germanium decreases d) copper decreases and germanium increases A capacitance transducer has two plates of area 5 cm2 each separated by an air gap of 2mm. Displacement sensitivity in pF /cm due to gap change would be - a) 11.1 b) 44.2 c) 52.3 d) 66.3 The critical angle in degrees, for an electromagnetic wave passing from Quartz (m = m0, Î=4Îo) into air is- a) 15 b)30 c)45 d)90 When an RC driving point impedance function has zeros at s= -2 and s=-5 then the admissible poles for the function would be – a) s = 0; s = -6 b) s = -1; s = -3 c) s = 0; s = -1 d) s = -3; s = -4 A capacitor used for power factor correction in single- phase circuit decreases – a) the power factor b) the line current c) Both the line current and the power factor d) the line current and increases power factor The unit of inductance is – a) ohm b) inductive reactance c) inducta d) Henry Which type of by-pass capacitor works best at high frequencies – a) electrolytic b) mica c) ceramic d) plexiglass The usual value of the surge impedance of a telephone line is – a) 600 W b) 500 W c) 75 W d) none Telemetering is a method of – a) counting pulses, sent over long distances b) transmitting pictures from one place to another c) transmitting information concerning a process over a distance d) None In an unbiased P-N junction thickness of depletion layer is of the order of – a) 0.005 mm b) 0.5 mm c) 5 mm d) 10-10 m One of the semiconductor device, which behaves like two SCRs is– a) UJT b) triac c) JFET d) MOSFET The following, which is not an advantage of semiconductor strain gauges as compared to conventional strain gauges, is – a) excellent hysterists characteristics b) least sensitive to temperature changes c) high fatigue life d) smaller size The fundamental ripple frequency of a half wave 3F rectifier with a 3F supply of frequency 50 Hz is – a) 150 Hz b) 50 Hz c) 100 Hz d) 250 Hz. For an FR biased PNP transistor – a) base is negative with respect to emitter b) collector is positive with respect to emitter c) collector is a little more positive than base d) base is a little less positive with respect to emitter than collector With normal operation of a JFET one can get IDss – a) the maximum drain current b) the minimum drain current c) normal drain current d) none An SCR is a semiconductor device made up of – a) Four N type layers b) Two P types and three N type layers c) Two P type and two N type layers d) Three P type and one N type layers For a UJT, if R1 = resistance from emitter to base 1, R2 = resistance from emitter to the base 2 and RBB = R1 + R2 then the intrinsic stand off ratio (h) is – a) b) c) d) As the drain voltage is increased for a junction FET in the pinch off region then the drain current – a) becomes zero b) abruptly decreases c) abruptly increases d) remains constant 20 When the energy gap of a semiconductor is 1.1eV then it would be – a) opaque to the visible light b) transparent to the visible light c) transparent to the infrared radiation d) opaque to the infrared radiation The equivalent capacitance across ab will be – d.0 In the following fig. the power dissipated is maximum when the value of Rx is – a) 33.4 K b) 17.6 K c) 10 K d) 5 K The transfer function of a low pass RC network is – The total capacitance across points 'a' and 'b' in the given figure is – a) 1.66 mF b) 2.66 mF c) 3.5 mF d) 4.5 mF The load resistance needed to extract maximum power from the following circuit is – a) 2W b) 9W c) 6W d) 18W Which one of the following conditions for z parameters would hold for a two port network containing linear bilateral passive circuit elements – a) z11 = z22 b) z12z21 = z11z22 c) z11z12 = z22z21 d) z12 = z21 In the network shown, the switch is opened at t = 0. Prior to that, the network was in the steady state, Vs(t) at t = 0 is – a) 0 b) 5V c) 10V d) 15V Which of the following statements are correct – 1. Tellegen's theorem is applicable to any lumped network 2. The reciprocity theorem is applicable to linear bilateral networks. 3. Thevenin's theorem is applicable to two terminal linear active networks. 4. Norton's theorem is applicable to two terminal linear active networks. a) 1, 2 and 3 b) 1, 2, 3 and 4 c) 1, 2 and 4 d) 3 and 4 Which one of the following transfer functions represents the critically damped system ? When the respective coil impedance of the circuit shown in the fig. is are Z1 = (5 + j8)W and Z2=(3+j8) then the input impedance of the circuit will be – a) (8 + 16j)W b) (2 + j0)W c) (15 + 64j)W d) (8 + 0j)W One of the following statement which is not correct - a) In case of an antenna, the radiation resistance and loss resistance are not two different quantities. b) The loss resistance includes loss by eddy currents, improper earth connections, insulation leakages etc) but not I2R losses c) Radiation resistance varies directly as square root of the frequency d) None of the above Ultraviolet radiation emitted when electron jumps from an outer stationary orbit to -. a) first stationary orbit b) second stationary orbit c) third stationary orbit d) fourth stationary orbit When the signal is propogated in a waveguide which has a full wave of electric intensity change between the two farther walls and no component of the electric field in the direction of propogation then the mode is – a) TE11 b) TE10 c) TM22 d) TE20 Consider the following statements pertaining to parabolic antenna - 1.It is commonly used above 1GHz 2. It get’s circularly polarized 3. It’s radiation pattern is highly directional 4. It’s radiation pattern is cardiod of these statements- a) 1,2 and 4 are correct b) 1 and 3 are correct c) 1,2 and 3 are correct d) 2 and 4 are correct When a vertical dipole antenna is used in conjunction with a loop antenna for direction finding, then the field pattern obtained will be- When one end of a loss less transmission line of length 3/8 l and characteristic impedance R0 is short circuited and the other end is terminated in Ro then the impedance at l/8 away from the end terminated in R0 is- a) Zero b) R0 c) R0/2 d) Infinite For transmission of wave from a dielectric permittivity Î1 into dielectric medium of lower permittivity Î2 (Î1 > Î2) the critical angle of incidence Qc ( relative to the interface ) is given by - A transmission line has primary constants R, L, G and C and secondary constants Z0 and g (= a + jb) if the line is loss less then . The intrinsic impedance of a free space is- One of the following which is a low gain but omni directional antenna is- a) discone b) log-periodic c) loop d) helical Electronic voltmeters have – a) high input impedance b) low input impedance c) zero input impedance d) none Which of the following statement about impulse voltage is true ? a) An impulse voltage is an unidirectional voltage. b) In chopped impulse voltage, flashover does not occur. c) Time taken to rise is exactly equal to the time taken to fall. d) RMS value of impulse voltage is always less than 50% of average value. The precision of an instrument indicates its ability to reproduce a certain reading with a given – a) drift b) resolution c) shift. d) consistency In heterodyne digital conductor, the input signal is heterodyned to a – a) higher frequency b) lower frequency c) both a and b) d) none In a digital measuring device, if the input electrical signal is in the frequency range dc to fmax Hz, then it must be sampled at a rate of – a) fmax times/sec b) fmax times/ses c) every 2fmax/sec d) 2 fmax times/sec . Moving Iron intruments measures the rms value of – a) a direct quantity b) an alternating quantity c) a virtual quantity. d) none.