Question

Shown below is a graph of current versus applied voltage for a diode. Approximately what is the resistance of the diode for an applied voltage of $-15V$?

• A. $2\Omega$
• B. $\infty$
• C. Zero
• D. $1\Omega$

Answer 1

Answer: (B)

$\infty$

The graph of current versus applied voltage for diode
In this case, at $-15V$, current in the circuit is zero.
Hence, according to Ohm's law,
$R=\frac{V}{l}=-\frac{1.5}{0}=\infty$
Alternate Method
Consider the current versus applied voltage graph given in the question. It is clear from the graph that the current flowing through the diode is zero at a voltage of $-1.5V$. Therefore, the diode is reverse biased at this voltage. As we know that, infinite resistance is offered by a diode in reverse biased condition. Thus, given diode has infinite $\left(\infty \right)$ resistance for the applied voltage of $-1.5V$.