If a $p-n$ junction diode is in forward bias,then:

In an unbiased $P-N$ junction,holes diffuse from the $p-$ region to $n-$ region because

In a $p-n$ junction diode, the current $I$ can be expressed as $I=I_{0} \left[\exp \left(\frac{e V}{k_{B} T}\right)-1\right]$, where $I_{0}$ is the reverse saturation current, $V$ is the voltage across the diode (positive for forward bias, negative for reverse bias), $I$ is the current through the diode, $k_{B}$ is the Boltzmann constant $(8.6 \times 10^{-5} \; eV/K)$, and $T$ is the absolute temperature. If for a given diode $I_{0}=5 \times 10^{-12} \; A$ and $T=300 \; K$, then:
$(a)$ What will be the forward current at a forward voltage of $0.6 \; V$?
$(b)$ What will be the increase in the current if the voltage across the diode is increased to $0.7 \; V$?
$(c)$ What is the dynamic resistance?
$(d)$ What will be the current if reverse bias voltage changes from $1 \; V$ to $2 \; V$?

$A$ diode having a potential difference of $0.5\, V$ across its junction,which does not depend on the current,is connected in series with a resistance of $20\, \Omega$ across a source. If $0.1\, A$ passes through the resistance,then what is the voltage of the source (in $, V$)?

The cause of the potential barrier in a $p-n$ junction diode is

Consider a $p-n$ junction as a capacitor, formed with $p$ and $n$-materials acting as thin metal electrodes and depletion layer width acting as separation between them. Basing on this, assume that an $n-p-n$ transistor is working as an amplifier in $CE$ configuration. If $C_1$ and $C_2$ are the base-emitter and collector-emitter junction capacitances, then :