My speciality. Овчинникова Т.Е - 10 стр.

of Figure 4 the A.C. plate resistance is given by QB/BR. For many diodes, the D.C.
plate resistance is approximately twice as great as the A.C. plate resistance.
5. It is clear from the figure that neither of these resistances is constant for all voltage,
and that both tend toward lower values as plate voltage and plate current are
increased .
6. If the plate of the diode is made negative with respect to the cathode, the electron
will be driven back to the cathode and no plate current will flow. Hence, if an
alternating voltage is applied to the plate, current will flow only in the positive half
cycles, and it will consist of a succession of pulses, always in the same direction. The
tube therefore function as a rectifier, in which an alternating voltage applied to the
tube produces a unidirectional current. Wide use is made of this characteristic to
obtain direct voltages and currents an A.C. source.
        Notes to the text

is responsible for – зависит от
unidirectional current – ток в одном направлении




Figure 1- Limitation of Diode      Figure 2- DC and AC Plate Resistance
Current by Space Charge


       2.1.3 Translate the word-combinations

a) space charge, plate resistance, internal plate circuit of the tube, direct current plate
resistance, positive half cycle, alternating current source.
b) temperature saturation is responsible for; limitation is caused by the presens of a
space charge; it cannot be expressed in terms of Ohm’s Law;
wide use is made of this characteristic.


       2.1.4 Answer the questions

1. When do electrons form a cloud of negative charges in the surrounding space? 2.
When could all the electrons eventually return to the cathode? 3. What is the useful
working range of nearly all vacuum tubes? 4. What is known as the D.C. Plate
resistance? 5. What is the D.C. plate resistance for many diodes? 6. In what cycles
will current flow if an alternating voltage is applied to the plate?