Vacuum Tubes Objectives Part 04

61 . The characteristic of triode shown in fig. 14 is known as mutual characteristics

62 . The value of plastic capacitances for a triode may range from 20 uf to 120uf

63 . In a triode parasitic capacitance may exist between 1. Plate and cathode 2. Plate and grid 3. grid and cathode 4.any of the above

64 . The value of parasitic capacitance of a triode increases as signal frequency increases

65 . The control grid of a triode is usually given negative potential with respect to the cathode so as to reduce the grid current to zero

66 . Under when plate voltage is less than the screen grid voltage conditions, the negative resistance region can be observed in a triode

67 . In a tetrode tube, secondary emission means the emission of electrons from the plate due to bombardment of the fast moving electrons emitted from the cathode.

68 . Mutual characteristic is the curve between plate current and grid voltage

69 . In pentode , the suppressor grid is placed between plate and screen grid

70 . In a pentode,the control grid is provided between cathode and screen grid

71 . In a pentode the suppressor grid is used to suppress secondary emission

72 . The suppressor grid in pentode eliminates the problem of secondary emission from the plate

73 . In a triode , tetrode or pentode, the plate current increase when the control grid voltage is made less negative

74 . The screen grid in a pentode decreases the grid plate capacitance as compared with a triode

75 . In a half wave rectified circuit the diode conducts when the plate is made positive by the positive alternation of the ac input voltage

76 . Diode Vacuum tube cannot be used as an amplifier

77 . Function of suppressor grid is

1 . Suppressor secondary emission effects 2.increase amplification factor 3.reduces Cgp

78 . A thermionic cathode is heated to emit electrons. T

79 . The anode has a positive potential with respect to the cathode to attract electrons. T

80 . In a diode, plate current can flow in only one direction. T