Question

The reverse bias in a junction diode is changed from $5V$ to $15V$ then the value of current changes from $38\mu A$ to $88\mu A$. The resistance of the junction diode will be
A. $4 \times {10^5}\Omega$
B. $3 \times {10^5}\Omega$
C. $2 \times {10^5}\Omega$
D. ${10^6}\Omega$

Answer 1

Resistance in general is given by voltage divided by current. In this situation the resistance in the junction diode is given by dividing the voltage change by the change in current. Use the data given in the question to calculate.

Complete step by step answer:
A diode is a P-N junction. It is typically a semiconductor device used to restrict the flow of current in a single direction only.
Reverse bias means that the positive terminal of the battery is connected with the negative terminal of the diode and vice versa. A diode generally works only on forward bias. However some diodes like the Zener diode work on reverse bias.
Given that the current changes from $5V$ to $15V$
And the voltage changes from $38\mu A$ to $88\mu A$
Thus resistance of the junction diode in reverse bias is given by change in voltage divided by change in current.
$R = \dfrac{{\Delta V}}{{\Delta I}} \\\ \Rightarrow R = \dfrac{{10}}{{50 \times {{10}^{ - 6}}}} \\\ \Rightarrow R = 0.2 \times {10^6} \\\ \therefore R = 2 \times {10^5}\Omega \\\$
Therefore the resistance of the junction diode is $R = 2 \times {10^5}\Omega$

So, the correct answer is “Option C”.

Note:
Students should know about the common terms related to diodes in forward and reverse bias of diodes. Forward bias means that the positive terminal of the diode is connected with the positive terminal of the power source and the negative terminal of the diode is connected with the negative terminal of the power source. For reverse bias it is just the opposite poles of the battery and diode are connected.