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

Two ideal diodes are connected to a battery as shown in the circuit. The current supplied by the battery is: (in $A$)

Which of the following is correct with respect to the following statements? Due to diffusion of electrons from $n$ to $p$-side:
$I$. electrons are accumulated in the depletion region.
$II$. electron drift current is from $p$-side to $n$-side.
$III$. an ionised donor is left in the $n$-region.
$IV$. electrons of $n$-side come to $p$-side and electron-hole combination takes place in $p$-side.
Select the correct option from the following.

$A$ $p-n$ junction diode is connected to a battery of emf $5.7 \ V$ in series with a resistor of $5 \ k\Omega$ such that it is forward biased. If the barrier potential of the diode is $0.7 \ V$,neglecting the diode resistance,the current in the circuit is:

What is threshold voltage? Write the value of threshold voltage for $Ge$ and $Si$.

In the following circuit of $PN$ junction diodes $D_1, D_2$ and $D_3$ are ideal,then the current $i$ is: