In the following figure,the diodes which are forward biased are:

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 $2 \; V$?

The current in the circuit will be:

The cut-in voltage for a silicon diode is approximately $V$.

Barrier potential of a $p-n$ junction diode does not depend on:

If the $p-n$ junction diode is unbiased,