PAPER : BSNL JTO Model Test Paper
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
Ans. a.) Schering bridge
2. LBDT is uses as a ?
a) . Displacement transducer
b.) Pressure transducer
d.) Any of the above
Ans. a). Displacement transducer
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
Ans. a.) Dielectric constant per unit volume
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
Ans. b.) High frequency response
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.
Ans. a.) ac property of the device at the desired operating point
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
d.) Delta V/Delta I
Ans. d). Delta V/Delta I
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
Ans. c. )Protect meter movement from stray magnetic fields
8. A capacitor that has been connected across a battery for comparatively long time becomes?
a. ) Charged
c.) Short - circuited
Ans. a. )Charged
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
Ans. c.) Q = CV
10. Silicon steel used for electrical purposes has silicon percentage of ?
a. ) 0.5
d) . None
Ans. c.) 3.4
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
Ans. c. )The ability to measure wider ranges of voltage and resistances
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
Ans. c.)Is higher than the centre of the energy gap
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
Ans. b. )depletion mode only
14. Consider the following semiconductor diodes ?
a. ) Germanium diode
b.) Silicon diode
c.) Tunnel diode
d.) Schottky diode
Ans. c.) Tunnel 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.
Ans. c.) peak value of ac supply exceeds the PIV value
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
Ans. c.) CB transfer 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
Ans. a.) positive with respect to the source
18. The SCR is often employed as a ?
a. ) Source-controlled switch
b. ) Drain-controlled switch
c.) Gate-controlled switch
Ans. c.) Gate-controlled switch
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
Ans.b.) Should be shunted by a 2pF capacitor
20. Compared to silicon, gallium arsenide (GaAs) has ?
a. ) Easier to grow crystals since the vapour pressure of arsenic is high
b. ) Higher optolectronic conversion efficiency
c.) Both a and b
d) . None
Ans. c.) Both a and b