The graph given below represents I-V characteristics of zener diode. The part of the characteristics curve that is most relevant for its operation as a voltage regulator is
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Zener Breakdown = Constant Voltage = Voltage Regulator.
Step 1: Understanding the Concept:
A Zener diode is a special type of diode designed to reliably allow current to flow "backwards" when a certain set reverse voltage, known as the Zener voltage, is reached.
It is heavily doped, which leads to a thin depletion region and a sharp breakdown voltage.
Its primary application is as a voltage regulator, maintaining a constant voltage across a load despite variations in input voltage or load current. Step 2: Key Formula or Approach:
For voltage regulation, a device needs to have a characteristic where voltage remains almost constant while current can vary significantly.
We need to look for this specific behavior on the provided I-V curve. Step 3: Detailed Explanation:
Let's analyze the given I-V characteristic curve:
- The section 'ab' lies in the first quadrant. This represents the forward-biased condition where the diode acts like a normal p-n junction diode. It is not used for voltage regulation here.
- The section 'c-d-e' lies in the third quadrant, representing the reverse-biased condition.
- The part 'cd' is the pre-breakdown region where a very small, almost constant reverse saturation current (leakage current) flows.
- At point 'd', the reverse voltage reaches the breakdown voltage (Zener voltage).
- The section 'de' shows a sharp, nearly vertical downward curve. In this region, a large change in current produces an almost negligible change in voltage.
This sharp breakdown region ('de') is where the Zener voltage remains constant over a wide range of reverse currents.
This precise characteristic allows it to be used as a voltage regulator. By operating the diode in this region, it maintains a stable output voltage.
Therefore, the part 'de' is the most relevant for its operation as a voltage regulator. Step 4: Final Answer:
The most relevant part of the curve is 'de'.
