Basic Electronics Mid - II, November - 2014

1.A system which has a capability to magnify a given signal is known as
  • Oscillator
  • Amplifier
  • Modulator
  • Integrated circuit
Answer: B
2.Negative feedback of an amplifier
  • Increases the voltage gain
  • Does not alter the voltage gain
  • Converts amplifier into oscillator
  • Decreases the voltage gain
Answer: D
3.The purpose of coupling capacitors in an amplifier is to
  • Match the impedance
  • Prevent the mixing of d.c with input or output
  • Limit the bandwidth
  • Control the output
Answer: B
4.The Barkhausen criterion for sustained oscillations is given by
  • Aβ=1
  • Aβ≥1
  • Aβ≤1
  • Aβ=180.
Answer: B
5.An R-C phase shift oscillator, the minimum number of R-C networks to be connected in cascade will be
  • One
  • Two
  • Three
  • Four
Answer: C
6.Oscillators use the following feedback
  • Negative
  • Positive
  • Both Negative and Positive
  • None
Answer: B
7.Resistance welding cannot be used for
  • Ferrous materials
  • Non-ferrous materials
  • Dielectrics
  • None
Answer: C
8.The voltage-current characteristic of a welding supply must be
  • drooping
  • rising
  • steady
  • none of the above
Answer: A
9.Induction heating takes place in
  • insulating materials
  • conducting and magnetic materials
  • conducting and non-magnetic materials
  • conducting materials may be conducting or magnetic materials
Answer: D
10.Power factor will be leading in case of
  • electric resistance heating
  • electric arc heating
  • dielectric heating
  • high frequency eddy current heating
Answer: C
11.An operational amplifier is basically a _________________________
Answer: High gain dc amplifier
12.Negative feedback in amplifiers reduces the gain but ___________ bandwidth
Answer: Increases
13.Feedback circuit is essentially a _______________
Answer: Potential divider
14.The operating frequency of a feedback oscillator is usually determined by an ______________ network.
Answer: Inductance-Capacitance
15.An LC network is sometimes called a ___________
Answer: Tank circuit
16.The amount of feedback developed by the Colpitts oscillator is based on the ______________
Answer: Capacitance ratio
17.The time taken for the welding current flows through the parts being welded is called as __________
Answer: Weld time
18.In dielectric heating, current flows through ______________
Answer: Dielectric
19.Steel pipes are manufactured by __________________ welding.
Answer: Resistance welding
20.The welding load is always ______________________
Answer: Intermittent