VIVA QUESTIONS:[1] What is a P-N junction diode?12] In this experiment, in which mode is the diode connected with the battery?13] What is the nature of a graph of P-N junction diode?14] What is knee voltage?[5] From the graph, what are the characteristics of P-N junction diode?olf P-N junction diode is in reverse biased condition with the battery, how will its characteristic be?[7] Which material is used in manufacturing a diode?[8] How are the nature of the graphs of P-N junction diode & Zener diode different?[9] Why is it necessary to set VR equal to zero before taking readings in this experiment?[10] What is the use of a diode in an electronic circuit?
Answers
1. i) P-N Junction diode is a piece of silicon with two terminals; one which is doped with P-type material and other is doped with N-type material.
ii)P-N junction diodes are the basic element of semiconductor diode.
2. In order to determine the mode, you can check the output voltage.
i) If you get positive output, it is in forward bias
ii) If you get negative output it is in reverse bias mode.
3. For forward bias,
i) Graph lies in the First quadrant.
ii) As voltage is increased initially, there is very less change in current but later, after threshold voltage a sudden rise is seen.
For reverse bias,
i) Graph lies in the third quadrant.
ii) As voltage is increased, initially no change is seen but after a particular voltage (breakdown voltage), current increases spectacularly.
4.In the Forward Biasing Mode, when the voltage is increased initially we see very minimal increase in current. At a certain voltage, current increases abruptly and massively. This voltage is known as knee voltage and this point on graph is knee point.
5. A P-N junction diode acts as a resistor for very low voltages but later acts as a conductor.
In the graph we can see that for forward and reverse bias, initially the current output is minimal but later conduction increases massively and suddenly. The voltage at which this happens is threshold voltage.
6.Nature of graph for reverse has been mentioned in question 4.
7. Material used can be Silicon, germanium, selenium.
8. i)Zener diode operates in both modes. A P-N junction diode can get destroyed if it is used in reverse biased heavily.
ii) Zener diode is sharply doped and P-N junction diode is moderately doped.
iii) Thus the graphs can be similar since both are diodes. Main difference is the applications and doping.
9. i) Vr is set to zero in order to disregard any existing voltage that exists in the circuit.
ii) Also, when set to zero, P-N junction diode has standard depletion region.
iii)To avoid any errors in reading, Vr shoul be set to zero.
10. Zener diodes can be used as voltage regulator while P-N diodes can be used as rectifiers.