What is the depletion region in pn junction?

The given circuit has two ideal diodes connected as shown in the figure below. The current flowing through the resistance $R_1$ will be

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R

Assertion A: Diffusion current in a $p-n$ junction is greater than the drift current in magnitude if the junction is forward biased.

Reason R: Diffusion current in a $p-n$ junction is form the $n$-side to the $p$-side if the junction is forward biased.

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

The $V-I$ characteristic of a diode is shown in the figure. The ratio of forward to reverse bias resistance is:

Identify the semiconductor devices whose characteristics are given below, in the order $\left(\mathrm{a}\right),\mathrm{ }\left(\mathrm{b}\right),\mathrm{ }\left(\mathrm{c}\right),\mathrm{ }\left(\mathrm{d}\right)$:

In a semiconductor diode, what is meant by a potential barrier?

$Ge$ and $Si$ diodes start conducting at $0.3 V$ and $0.7 V$ respectively. In the following figure if $Ge$ diode connection are reversed, the value of $V_0$ changes by: (assume that the Ge diode has large breakdown voltage)