A Zener of power rating $1\, W$ is to be used as a voltage regulator. If zener has a breakdown of $5\,V$ and it has to regulate voltage which fluctuated between $3\,V$ and $7\,V$, what should be the value of $R_s$ for safe operation (See figure) ?

Given below are two statements:

Statement $I$ : Photovoltaic devices can convert optical radiation into electricity.

Statement $II$ : Zener diode is designed to operate under reverse bias in breakdown region.

In the light of the above statements, choose the most appropriate answer from the options given below

A certain $p-n$ junction, having a depletion region of width $20 \,\mu m$, was found to have a breakdown voltage of $100 \,V$. If the width of the depletion region is reduced to $1 \,\mu m$ during its production, then it can be used as a zener diode for voltage regulation of ………. $V$

In a Zener regulated power supply a Zener diode with $V_{z}=6.0\; V$ is used for regulation. The load current is to be $4.0 \;mA$ and the unregulated input is $10.0\; V$. What should be the value of series resistor $R_{S} ?$

In the given circuit what is the maximum value of $R_S$ for zener diode to regulate voltage on load resistance ?…….$K\Omega $