1. A vacuum tube has electrodes confined inside an evacuated
(a) glass envelope only (b) metal envelope only
(c) either of (a) and (b) above (d) none of the above
2. In which of the following application vacuum tubes are still being used?
(a) public address system (b) radio receivers
(c) radio transmitters (d) electroplating plants
3. Vacuum tubes in a radio transmitter are used to
(a) provide dc supply (b) generate high power radio waves
(c) record programs (d) provide lighting inside the studio
4. Transistors have not replaced vacuum tubes because
(a) transistors are non-linear
(b) transistors do not have grid
(c) high power transistors are not available
(d) heat dissipation from transistors is difficult
5. Vacuum tubes are still used in some electronic device due to
(a) their long life
(b) their trouble free life
(c) their capacity to handle high power
(d) their better reliability
6. The emission of electrons in a vacuum diode is achieved by
(a) electrostatic field (b) magnetic field
(c) heating (d) electron bombardment
7. At ordinary temperatures, energy of free electrons in metals as compared with work function is
(a) more (b) less
(c) equal (d) none of the above
8. The energy can be provided to electrons to cross the surface barrier by
(a) heating (b) electric field
(c) light (d) any of the above
9. The principle of emission of electrons from a metal surface, under the influence of light is known as
(a) photo electric emission (b) seebeck effect
(c) secondary emission (d) none of the above
10. With an indirectly heated cathode, the heater voltage
(a) must be a steady dc voltage (b) is applied to the cathode
(c) is separate from the cathode circuit
(d) none of the above
11. Secondary emission of electrons occurs when the metal surface is
(a) cooled to very low temperatures (b) heated
(c) subjected to electric as well as magnetic field
(d) bombardment with high energy electrons
12. The filament of a vacuum tube can be heated by
(a) dc voltage only (b) low frequency ac voltage
(c) rectified dc voltage (d) any of the above
13. The work function for the oxide coated emitter material is
(a) 1.0 eV (b) 2.63 eV
(c) 3.98 eV (d) 4.52 eV
14. The work function of pure tungsten is
(a) 1.5 eV (b) 2.5 eV
(c) 8.5 eV (d) 4.5 eV
15. Oxide coated cathodes are used for the tubes
(a) designed to handle small power
(b) designed to handle large power
(c) used in radio transmitters
(d) none of the above
16. The emission efficiency of a cathode is
(a) emission current/volt
(b) emission current/0C
(c) emission current/W
(d) emission current/electron density
17. A directly heated cathode may be made of
(a) tungsten
(b) thoriated tungsten
(c) tungsten coated with strontium oxide
(d) any of the above
18. In case of indirectly heated tubes the heater filament is usually made of
(a) manganin (b) tungsten
(c) invar (d) any of the above
19. The anode material is usually
(a) nickel (b) carbon
(c) copper (d) aluminium
20. Fins are often provided on
(a) heater filament (b) cathode
(c) anode (d) all of the above
21. In triodes, the grid is made in the form of
(a) single filament wire (b) metal strip
(c) mesh (d) metallic cylinder
22. In a troide, the third electrode is kept
(a) near the cathode (b) near the anode
(c) exactly in between cathode and anode
(d) anywhere between cathode and anode
23. Which of the following vacuum tube cannot be used as an amplifier?
(a) Diode (b) Triode
(c) Tetrode (d) Pentode
24. The process by which impurities are added to a pure semi-conductor is
(a) Diffusing (b) Drift
(c) Doping (d) Mixing
25. Which of the following is a passive component?
(a) Semi-conductor device (b) Vacuum tube device
(c) Capacitors (d) All of the above
26. A Germanium atom contains
(a) Two electron orbits (b) Three valence electrons
(c) Four protons (d) Four valance electron
27. The type of atomic bonding most common in semi-conductor is
(a) Metallic (b) Ionic
(c) Covalent (d) Chemical
28. When at atom either gains or loses an electron it is said to be
(a) Ionized (b) Bonded
(c) Excited (d) Stablised (e) An acceptor
29. The diameter of an atom is
(a) 10-6 metre (b) 10-10 metre
(c) 10-15 metre (d) 10-21 metre
30. The atomic weight of an atom is determined by
(a) The number of protons
(b) The number of neutrons
(c) The number of protons and neutrons
(d) The number of electrons and protons
31. The constituents of an atoms are
I. Protons II. Neutrons
III. Electrons IV. Positron
The mass of which two constituents is nearly the same?
(a) I and II only (b) II and III only
(c) I and III only (d) II and IV only
32. The number of protons in an atom is called its
(a) isotope number (b) atomic number
(c) atomic weight (d) none of the above
33. The maximum number of electrons in third orbit can be
(a) 3 (b) 6
(c) 12 (d) 18
34. Valence electrons are the
(a) loosely packed electrons (b) mobile electrons
(c) electrons present in the outermost orbit
(d) electrons that of not carry any charge
35. Which of the following element has lowest atomic number?
(a) B (b) Al
(c) Ga (d) In
36. Which of the following element has four valence electrons?
(a) Silicon (b) Germanium
(c) Both (a) and (b) above (d) None of the above
37. Which of the following element has four valance electrons?
(a) Silicon (b) Antimony
(c) Phosphorous (d) Boron
38. The forbidden energy gap for germanium is
(a) 0.12 eV (b) 0.32 eV
(c) 0.72 eV d) 0.92 eV
39. Free electrons exist in
(a) First band (b) Second band
(c) Third band (d) Conduction band
40. The advantage of transistor over vacuum tube is
(a) no heat is required
(b) small size and light in weight
(c) very low power consumption
(d) all of the above
41. A collector collects
(a) electrons from the base in case of PNP transistor
(b) electrons from the emitter in case PNP transistor
(c) holes from the base in case of NPN transistor
(d) holes from the base in case of PNP transistor
42. A PNP transistor is made of
(a) Silicon (b) Germanium
(c) Either silicon or germanium (d) None of the above
43. A transistor which of the following region is very lightly doped and is very thin?
(a) Emitter (b) Base
(c) Collector (d) None of the above
44. In a PNP transistor, with normal bias, the emitter junction
(a) is always reverse biased (b) offers very high resistance
(c) offers a low resistance (d) remains open
45. In a NPN transistor, when emitter junction is forward biased and collector junction is reverse biased, the transistor will operate in
(a) active region (b) saturation region
(c) cut off region (d) inverted region
46. In a PNP transistor, electrons flow
(a) into the transistor at the collector only
(b) into the transistor at the base and the collector leads
(c) out of the transistor at base, and collector leads
(d) out of the transistor at base collector as well as emitter leads
47. A transistor may fail due to
(a) open weld at the wire leads to the semiconductor
(b) short circuit caused by momentary overloads
(c) overheating due to circuit failures
(d) any of the above
48. Arrow head on a transistor symbol indicates
(a) Direction of electron current in emitter
(b) direction of hole current in emitter
(c) different current in emitter
(d) drift current in emitter
49. The heat sink disposes off heat mainly by
(a) radiation (b) natural convection
(c) forced convection (d) conduction
50. A transistor has
I. Collector
II. Emitter
III. Base
In a PNP transistor the electron flow into the transistor at
(a) I only (b) II only
(c) II and III only (d) I and III only1. A vacuum tube has electrodes confined inside an evacuated
(a) glass envelope only (b) metal envelope only
(c) either of (a) and (b) above (d) none of the above
2. In which of the following application vacuum tubes are still being used?
(a) public address system (b) radio receivers
(c) radio transmitters (d) electroplating plants
3. Vacuum tubes in a radio transmitter are used to
(a) provide dc supply (b) generate high power radio waves
(c) record programs (d) provide lighting inside the studio
4. Transistors have not replaced vacuum tubes because
(a) transistors are non-linear
(b) transistors do not have grid
(c) high power transistors are not available
(d) heat dissipation from transistors is difficult
5. Vacuum tubes are still used in some electronic device due to
(a) their long life
(b) their trouble free life
(c) their capacity to handle high power
(d) their better reliability
6. The emission of electrons in a vacuum diode is achieved by
(a) electrostatic field (b) magnetic field
(c) heating (d) electron bombardment
7. At ordinary temperatures, energy of free electrons in metals as compared with work function is
(a) more (b) less
(c) equal (d) none of the above
8. The energy can be provided to electrons to cross the surface barrier by
(a) heating (b) electric field
(c) light (d) any of the above
9. The principle of emission of electrons from a metal surface, under the influence of light is known as
(a) photo electric emission (b) seebeck effect
(c) secondary emission (d) none of the above
10. With an indirectly heated cathode, the heater voltage
(a) must be a steady dc voltage (b) is applied to the cathode
(c) is separate from the cathode circuit
(d) none of the above
11. Secondary emission of electrons occurs when the metal surface is
(a) cooled to very low temperatures (b) heated
(c) subjected to electric as well as magnetic field
(d) bombardment with high energy electrons
12. The filament of a vacuum tube can be heated by
(a) dc voltage only (b) low frequency ac voltage
(c) rectified dc voltage (d) any of the above
13. The work function for the oxide coated emitter material is
(a) 1.0 eV (b) 2.63 eV
(c) 3.98 eV (d) 4.52 eV
14. The work function of pure tungsten is
(a) 1.5 eV (b) 2.5 eV
(c) 8.5 eV (d) 4.5 eV
15. Oxide coated cathodes are used for the tubes
(a) designed to handle small power
(b) designed to handle large power
(c) used in radio transmitters
(d) none of the above
16. The emission efficiency of a cathode is
(a) emission current/volt
(b) emission current/0C
(c) emission current/W
(d) emission current/electron density
17. A directly heated cathode may be made of
(a) tungsten
(b) thoriated tungsten
(c) tungsten coated with strontium oxide
(d) any of the above
18. In case of indirectly heated tubes the heater filament is usually made of
(a) manganin (b) tungsten
(c) invar (d) any of the above
19. The anode material is usually
(a) nickel (b) carbon
(c) copper (d) aluminium
20. Fins are often provided on
(a) heater filament (b) cathode
(c) anode (d) all of the above
21. In triodes, the grid is made in the form of
(a) single filament wire (b) metal strip
(c) mesh (d) metallic cylinder
22. In a troide, the third electrode is kept
(a) near the cathode (b) near the anode
(c) exactly in between cathode and anode
(d) anywhere between cathode and anode
23. Which of the following vacuum tube cannot be used as an amplifier?
(a) Diode (b) Triode
(c) Tetrode (d) Pentode
24. The process by which impurities are added to a pure semi-conductor is
(a) Diffusing (b) Drift
(c) Doping (d) Mixing
25. Which of the following is a passive component?
(a) Semi-conductor device (b) Vacuum tube device
(c) Capacitors (d) All of the above
26. A Germanium atom contains
(a) Two electron orbits (b) Three valence electrons
(c) Four protons (d) Four valance electron
27. The type of atomic bonding most common in semi-conductor is
(a) Metallic (b) Ionic
(c) Covalent (d) Chemical
28. When at atom either gains or loses an electron it is said to be
(a) Ionized (b) Bonded
(c) Excited (d) Stablised (e) An acceptor
29. The diameter of an atom is
(a) 10-6 metre (b) 10-10 metre
(c) 10-15 metre (d) 10-21 metre
30. The atomic weight of an atom is determined by
(a) The number of protons
(b) The number of neutrons
(c) The number of protons and neutrons
(d) The number of electrons and protons
31. The constituents of an atoms are
I. Protons II. Neutrons
III. Electrons IV. Positron
The mass of which two constituents is nearly the same?
(a) I and II only (b) II and III only
(c) I and III only (d) II and IV only
32. The number of protons in an atom is called its
(a) isotope number (b) atomic number
(c) atomic weight (d) none of the above
33. The maximum number of electrons in third orbit can be
(a) 3 (b) 6
(c) 12 (d) 18
34. Valence electrons are the
(a) loosely packed electrons (b) mobile electrons
(c) electrons present in the outermost orbit
(d) electrons that of not carry any charge
35. Which of the following element has lowest atomic number?
(a) B (b) Al
(c) Ga (d) In
36. Which of the following element has four valence electrons?
(a) Silicon (b) Germanium
(c) Both (a) and (b) above (d) None of the above
37. Which of the following element has four valance electrons?
(a) Silicon (b) Antimony
(c) Phosphorous (d) Boron
38. The forbidden energy gap for germanium is
(a) 0.12 eV (b) 0.32 eV
(c) 0.72 eV d) 0.92 eV
39. Free electrons exist in
(a) First band (b) Second band
(c) Third band (d) Conduction band
40. The advantage of transistor over vacuum tube is
(a) no heat is required
(b) small size and light in weight
(c) very low power consumption
(d) all of the above
41. A collector collects
(a) electrons from the base in case of PNP transistor
(b) electrons from the emitter in case PNP transistor
(c) holes from the base in case of NPN transistor
(d) holes from the base in case of PNP transistor
42. A PNP transistor is made of
(a) Silicon (b) Germanium
(c) Either silicon or germanium (d) None of the above
43. A transistor which of the following region is very lightly doped and is very thin?
(a) Emitter (b) Base
(c) Collector (d) None of the above
44. In a PNP transistor, with normal bias, the emitter junction
(a) is always reverse biased (b) offers very high resistance
(c) offers a low resistance (d) remains open
45. In a NPN transistor, when emitter junction is forward biased and collector junction is reverse biased, the transistor will operate in
(a) active region (b) saturation region
(c) cut off region (d) inverted region
46. In a PNP transistor, electrons flow
(a) into the transistor at the collector only
(b) into the transistor at the base and the collector leads
(c) out of the transistor at base, and collector leads
(d) out of the transistor at base collector as well as emitter leads
47. A transistor may fail due to
(a) open weld at the wire leads to the semiconductor
(b) short circuit caused by momentary overloads
(c) overheating due to circuit failures
(d) any of the above
48. Arrow head on a transistor symbol indicates
(a) Direction of electron current in emitter
(b) direction of hole current in emitter
(c) different current in emitter
(d) drift current in emitter
49. The heat sink disposes off heat mainly by
(a) radiation (b) natural convection
(c) forced convection (d) conduction
50. A transistor has
I. Collector
II. Emitter
III. Base
In a PNP transistor the electron flow into the transistor at
(a) I only (b) II only
(c) II and III only (d) I and III only