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Starting electronics
a – symbol, they don’t necessarily have to be positive and
negative. The cathode could for example be at a voltage of
+1000 V if the anode was at a greater positive voltage of, say
+1001 V. All that needs to occur is that the anode is positive
with respect to the cathode.
Under such a condition, the diode is said to be forward biased
and current will flow, from anode to cathode.
When a diode is reverse biased i.e., its cathode is positive
with respect to the anode, no current flows, as shown in Figure
6.6(b). Obviously, something happens within the diode
which we can’t see, depending on the polarity of the applied
voltage to define whether current can flow or not. Just exactly
what this something is, isn’t necessary to understand
Figure 6.6
Circuit diagrams for forward and reverse biased diodes
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