CBSE Class 12 · 2008 · All India · SemiconductorsShort Answer

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Draw the
(i) symbol and
(ii) the reverse I-V characteristic of a zener diode. Explain briefly which property of the characteristic enables us to use the zener diode as a voltage regulator.

Solution

The symbol of a zener diode is a diode symbol with a bent (Z-shaped) bar at the cathode.
In reverse bias the current is small until

V_{z}

, beyond which it rises steeply while the voltage across the diode remains essentially constant at

V_{z}

.
Because the voltage stays fixed at

V_{z}

over a wide range of current, the zener diode holds the output voltage constant and thus acts as a voltage regulator.

Constant voltage in reverse breakdown \Rightarrow regulation.

CBSE Class 12 Board · 2008 · All India · Subjective

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