In the case of forward biasing of a $PN-$ junction,which one of the following figures correctly depicts the direction of flow of majority charge carriers?

$A$ potential barrier of $0.4 \,V$ exists across a p-n junction. An electron enters the junction from the $n$-side with a speed of $6.0 \times 10^{5} \,ms^{-1}$. The speed with which the electron enters the $p$-side will be $\frac{x}{3} \times 10^{5} \,ms^{-1}$. The value of $x$ is ..............
(Given: mass of electron $= 9 \times 10^{-31} \,kg$,charge on electron $= 1.6 \times 10^{-19} \,C$.)

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

$A$ semiconductor $(Ge - As)$ has an energy gap of $1.43\, eV.$ What is the maximum wavelength emitted when a hole and an electron recombine in such semiconductor in $\mathring{A}$?

The reverse biasing in a $PN$ junction diode

In the following diode circuits,which diode is in a forward-biased condition?