NCERT Solutions for Chapter: Semiconductor Electronics: Materials, Devices and Simple Circuits, Exercise 2: VSA

Why are elemental dopants for Silicon or Germanium usually chosen from group $\mathrm{XIII}$ or group $\mathrm{XV}$?

$\mathrm{Sn}, \mathrm{C},$ $\mathrm{Si}, \mathrm{Ge}$ are all group $\mathrm{XIV}$ elements. Yet, $\mathrm{Sn}$ is a conductor, $\mathrm{C}$ is an insulator while $\mathrm{Si}$ and $\mathrm{Ge}$ are semiconductors.Why?

Can the potential barrier across a $\mathrm{p}-\mathrm{n}$ junction be measured by simply connecting a voltmeter across the junction?

Draw the output waveform across the resistor.

The amplifiers $\mathrm{X}, \mathrm{Y}$ and $\mathrm{Z}$ are connected in series. If the voltage gains of $\mathrm{X}, \mathrm{Y}$ and $\mathrm{Z}$ are $10, 20$ and $30$, respectively and the input signal is $1 \mathrm{mV}$ peak value, then what is the output signal voltage (peak value)

(i) if $\mathrm{dc}$ supply voltage is $10\mathrm{V}$?

(ii) if $\mathrm{dc}$ supply voltage is $5\mathrm{V}$?

In a $\mathrm{CE}$ transistor amplifier there is a current and voltage gain associated with the circuit. In other words there is a power gain. Considering power a measure of energy, does the circuit voilate conservation of energy?