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
