Question

A Zener diode having break-down voltage $5.6\text{V}$ is connected in reverse bias with a battery of emf $10\text{V}$ and a resistance of $100\Omega$ in series. The current flowing through the Zener is

• A. $4.4\text{mA}$
• B. $44\text{mA}$
• C. $2.2\text{mA}$
• D. $22\text{mA}$

Answer 1

The correct option is B $44\text{mA}$

A Zener diode offers infinite resistance as long as the reverse voltage across it is less than the break-down value.

As soon as the reverse bias voltage cross the break-down level, the residue voltage remains in the circuit, with the diode offering zero resistance to it.

Hence, here the voltage remaining across the Zener

$=10-5.6=4.4\text{V}$

Therefore, the current in the circuit is

$I_Z=\frac{4.4}{100}=4.4\times {10}^{-2}\text{A}=44\text{mA}$

Hence, $\left(B\right)$ is the correct answer.