question_answer

Different voltages are applied across a p-n junction and the currents are measured from each value. Which of the following graphs is obtained between voltage and current?

A)  

B)  

C)  

D)  

Correct Answer: A

Solution :

When the junction diode is forward biased, i.e., p -side is kept at higher potential, the current in the diode changes with the voltage applied across the diode. The current increases very slowly till the voltage across the diode crosses a certain value. After this voltage, the diode current increases rapidly even for very small increase in the diode voltage. The current-voltage relation for diode is shown. Note: The value of the cut-in voltage is about 0.2 V for a germanium diode and 0.7 V for a silicon diode.