Question 51 of 209

A zener diode of power rating $1.6W$ is to be used as voltage regulator. If the zener diode has a breakdown of $8V$ and it has to regulate voltage fluctuating between $3V$ and $10V$ The value of resistance ${R}_{s}$ for safe operation of diode will be

A$10\Omega$B$12\Omega$C$13.3\Omega$D$13\Omega$

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Answer: (A) $10\Omega$

Power rating of zener diode $=1.6W$
From the diagram above,
${V}_{A}-{V}_{B}=8V$
Power is given by
$P=Vi \Rightarrow i=\dfrac{1.6W}{8V}=0.2A$
Also, ${V}_{C}-{V}_{A}=10V-8V=2V$
Thus, using Ohm's law,
${R}_{s}=\dfrac{2V}{0.2A}=10\Omega$