Q.The symbol of a diode is shown in the figure :

A Zener diode maintains a constant voltage across its terminals in reverse breakdown, making it the standard voltage regulator.

A Zener diode is designed to operate in the reverse breakdown region. Once the reverse voltage reaches the Zener voltage, the voltage across the diode stays almost constant even though the current through it varies over a wide range. Connected across a load, it therefore holds the output voltage steady against changes in supply voltage or …

A Zener diode's circuit symbol is the ordinary diode symbol with the straight cathode line replaced by a bent (Z-shaped) line.

A Zener diode is drawn like an ordinary p-n junction diode — a triangle (representing the p-region/anode) pointing toward a straight bar (representing the n-region/cathode), the arrow showing the conventional (easy, forward) direction of current flow, anode to cathode.

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Unlike an ordinary diode, a Zener diode is deliberately operated in reverse breakdown, where the voltage across it stays nearly constant over a range of currents.

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Operated in reverse breakdown, a Zener diode holds a fixed voltage across itself regardless of current variations, so it is used as a voltage regulator.

Working

A Zener diode is a specially designed p-n junction diode intended to be operated in the reverse breakdown region without being damaged (heavily doped junction). In this region, the voltage across the diode stays almost constant over a wide range of reverse currents. This property is exploited to hol …

A correctly biased Zener diode maintains a constant voltage across itself.

A Zener diode is operated in reverse bias at its breakdown (Zener) voltage. In this region the voltage across it stays almost constant even as the current through it changes widely. This makes it ideal as a voltage regulator. T …

A Zener diode is used as a voltage regulator because its reverse breakdown voltage stays nearly constant.

A voltage regulator must hold its output voltage essentially fixed even when the input voltage or the load current varies. A Zener diode, when connected in reverse bias beyond its breakdown (Zener) voltage $V_Z$, carries a wide range of current while the voltage across it stays almost constant at $V_Z$. By placing the Zener diode in parallel with the load (through a series resistor from the unregulated supply), any excess current is diverted through the diode, keeping the lo …

A zener diode is designed to work in the reverse breakdown region, so it is always connected in reverse bias.

An ordinary p-n junction diode is destroyed if driven into reverse breakdown, but a zener diode is specially doped (heavily doped p and n regions) so that it can withstand a sharp, well-defined reverse breakdown voltage ($V_Z$) without damage. Once the reverse voltage reaches $V_Z$, the current increases sharply while the voltage across the diode stays almost constant at $V_Z$.

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