BSNL question papers- part-2

1. Reactive current through the inductive load produces-
a) Magnetic field
b) Electric field
c) Super magnetic field
d) None

2. 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

3. 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

4. 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

5. 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

6. 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

7. The unit of inductance is –
a) ohm
b) inductive reactance
c) inducta
d) Henry

8. Which type of by-pass capacitor works best at high frequencies –
a) electrolytic
b) mica
c) ceramic
d) plexiglass

9. The usual value of the surge impedance of a telephone line is –
a) 600 W
b) 500 W
c) 75 W
d) none

10. 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

11. 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

12. One of the semiconductor device, which behaves like two SCRs is–
a) UJT
b) triac
c) JFET
d) MOSFET

13. 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

14. 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.

15. 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

16. 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

17. 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

18. 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

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