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Basic Electronics

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Basic Electronics

shape Introduction

Basic Electronics is a first step towards understanding electronic circuits and electronic components. Basic Electronic component is any basic discrete device or physical entity in an electronic system used to affect electrons or their associated fields. An electronic circuit is a structure or a closed loop that directs and controls electric currents, presumably to perform some useful function. Electric Current is the flow of electric charge, which is usually just called charge.

shape Quiz

Q1. An ideal diode
    A. should have zero resistance in the forward bias and zero resistance in the reverse bias B. should have infinite large resistance in the reverse bias C. should have zero resistance in the forward bias and an infinitely large resistance in the reverse bias D. none of these Answer: C

Q2. Vacuum tubes in a radio transmitter are used to
    A. record programmes B. d.c. supply C. generate high power radio waves D. none of these Answer: C

Q3. Which of the following electron emission process is widely used vacuum tubes?
    A. Thermionic emission B. Secondary emission C. Photoelectric emission D. None of these Answer: A

Q4. Which of the following semiconductors has the highest melting point ?
    A. Gallium arsenide B. Germanium C. Silicon D. None of these Answer: C

Q5. Power diodes are generally
    A. germanium diodes B. silicon diodes C. both (a) and (b) D. none of these Answer: B

Q6. In PN junction, the region containing the uncompensated acceptor and donor ions is called
    A. active region B. natural region C. both (a) and (b) D. depletion region Answer: D

Q7. The photoelectric current in amperes per watt of incident light depends upon
    A. intensity of incident light B. frequency of incident light C. both (a) and (b) D. none of these Answer: B

Q8. In case of semiconductors, recombination is
    A. merging of two or more holes B. merging of an just energed electron with resulting hole in the semi-conductor C. both (a) and (b) D. none of the above Answer: B

Q9. Vacuum diode is a two-electrode vacuum tube, first is called cathode and the second is called
    A. symbol B. rectifier C. anode D. none of these Answer: C

Q10. Which of the following emitter material usually needs less than 1000V as plate voltage?
    A. Pure tungsten B. Oxide coated C. Both (a) and (b) D. None of these Answer: B
Q11. In a diode the plate current increases when the
    A. saturation plate current is reached B. plate voltage is made more positive C. plate voltage is made less positive D. none of these Answer: B

Q12. The maximum charge carried by an ion is
    A. equal to the charge of number of electrons gained or lost by the atom on ionization B. zero C. equal to the charge of electrons left in the atom D. none of these Answer: A

Q13. The forbidden energy gap in semiconductors
    A. lies between the valence band and the conduction band B. lies above the conduction band C. is always zero D. none of these Answer: A

Q14. For a PN junction diode, the current in reverse bias may be
    A. few micro or nano amperes B. few amperes C. between 0.25 and 1A D. none of these Answer: A

Q15. For d.c. power supply, diode can be used as a detector and a
    A. emitter B. rectifier C. either (a) and (b) D. none of these Answer: B

Q16. The bulk resistance of a diode is
    A. the resistance of P and N materials B. the resistance of junction only C. the resistance of P material only D. the resistance of N material only Answer: A

Q17. The emission of electrons in a vacuum diode is achieved by
    A. heating B. magnetic field C. electric field D. none of these Answer: A

Q18. A full were bridge rectifier is supplied voltage at 50Hz. The lowest ripple frequency will be
    A. 100 Hz B. 95 Hz C. 75 Hz D. 225 Hz Answer: A

Q19. Which of the following results in the movement of a hole?
    A. A vacancy is filled by a valence electron from the neighbouring atom B. Moment of protons C. Moment of neutrons D. None of the above Answer: A

Q20. For vacuum tubes the negative grid voltage of smallest magnitude required to make the plate current zero is called:
    A. Cut-off grid voltage B. Minimum grid voltage C. Both (a) and (b) D. None of these Answer: B
Q21. When the cathode of vacuum tube is heated and anode is not connected to any external circuit
    A. electrons form a space charge B. protons are emitted from anode C. glass tube gets charged D. none of these Answer: A

Q22. Oxide coated cathodes are used for the tubes
    A. used in radio transmitters B. Power Rectifiers C. designed to handle small power D. none of the above Answer: C

Q23. The maximum forward current in case of low power signal diode is in the range of
    A. few milli-amperes B. 0.1 A to 0.5 A C. 1 A to 2.5 A D. 1.25 A to 3.25 A Answer: A

Q24. When PN junction is in forward bias, by increasing the battery voltage
    A. current through PN junction increases B. circuit resistance increases C. both (a) and (b) D. none of these Answer: A

Q25. The principle of emission of electrons from a metal surface, under the influence of light is known as
    A. secondary emission B. photoelectric emission C. thermionic emission D. none of these Answer: B

Q26. The bandwidth of a difference amplifier is comparable to that of a
    A. single-stage CE amplifier B. double-stage CE amplifier C. cascade amplifier D. Darlington amplifier Answer: C

Q27. Which of the following transistors can be used in enhancement mode?
    A. UJT B. JFET C. MOSFET D. NPN transistor Answer: C

Q28. Zener diodes
    A. have breakdown voltage of less than 5V and have a -ve temperature coefficient B. have breakdown voltage of less than 5V and have a +ve temperature coefficient C. have breakdown voltage of more than 5V and have a +ve temperature coefficient D. have breakdown voltage of 5 V and have a zero temperature coefficient Answer: A

Q29. In a semiconductor, the movement of holes is due to
    A. movement of electrons in conduction band B. movement of holes in conduction band C. movement of holes in valence band D. movement of electrons in valence band Answer: D

Q30. In a CE transistor amplifier, if collector-emitter voltage increases, the instantaneous operating point
    A. moves up the load line B. moves down the load line C. moves at right angles to the load line D. remains stationary Answer: A
Q31. When a P-N junction is forward biased
    A. the width of the depletion layer is decreased B. the width of depletion layer is increased C. the width of the depletion layer remains the same D. none of these Answer: A

Q32. One disadvantage of directly coupled transistor amplifier is that
    A. identical transistors are required B. both NPN transistors are required C. variations in current due to temperature changes in one stage are amplified by other stages D. the low frequency response is poor Answer: C

Q33. A UJT has
    A. stable negative resistance characteristics B. low firing current C. use as a waveform generator D. all of these characteristics Answer: A

Q34. In a properly biased transistor
    A. both depletion regions are large B. both depletion regions are small C. the emitter to base depletion region is small and collector to base depletion region is large D. the emitter to base depletion region is large and collector to base depletion region is small Answer: C

Q35. Dynamic resistance is the ratio of
    A. change in drain-source voltage and change in drain current at constant VGS B. change in gate-source voltage and change in drain current at constant VDS C. Drain-source voltage and drain current D. gate-source voltage and drain current Answer: A

Q36. The ratio of diffusion constant for electrons De to themobility for electrons me is
    A. independent of T B. inversely proportional to T C. proportional to T2 D. proportional to T Answer: D

Q37. The addition of trivalent impurity to an intrinsic semiconductor creates
    A. N-type semiconductor B. excess free electrons C. excess holes D. electron-hole pairs Answer: C

Q38. In a full wave rectifier circuit the peak inverse voltage per diode is
    A. the same as that in a half wave circuit B. half the value in a half wave circuit C. double the value in a half wave circuit D. none of above Answer: C

Q39. The potential barrier acts as a barrier against the flow of
    A. electrons only B. holes only C. electrons and holes D. None of these Answer: C

Q40. The number of valence electron in boron is
    A. 1 B. 2 C. 3 D. 5 Answer: C
Q41. When an electron breaks a covalent bond and moves away
    A. the semiconductor becomes conductor B. a valency is created in broken covalent bond C. the conductivity of the material increase D. more ions are produced Answer: B

Q42. The conduction band is
    A. the region of free electrons B. a range of energies corresponding to the energies of the free electrons C. always above the forbidden energy level D. con centrated holes for the flow of current Answer: B

Q43. The merging of a free electron and a hole is known as
    A. recombination B. extrusion C. absorption D. adsorption Answer: A

Q44. The majority charge carriers in an n-type semiconductors are
    A. holes B. electrons C. neutrons D. None of these Answer: B

Q45. Which of the following are immobile?
    A. Electrons B. Holes C. Ions D. None of these Answer: C

Q46. The transferred-electron bulk effect occurs in
    A. silicon B. germanium C. gallium D. metal semiconductor junction Answer: C

Q47. What type of electron carriers in n-type semiconductor?
    A. Minority B. Majority C. Both (a) and (b) D. None of these Answer: B

Q48. Which of the following has the highest mobility?
    A. Neutron B. Electron C. Positive ions D. Negative ions Answer: B

Q49. In p-n junction with no external voltage, the electric field between the acceptor and the donor ions is called a
    A. barrier B. threshold C. peak D. path Answer: A

Q50. In a p-n junction the potential barrier is due to the charges on either side of the junction. These charges are
    A. majority carriers B. minority carriers C. both majority as well as minority carriers D. fixed donor and acceptor ions Answer: D
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