$A$ $P-N$ junction has a potential barrier of $0.5 \ V$. If an electron enters the $P-N$ junction diode from the $N$-side with a speed of $5 \times 10^5 \ m/s$,what will be its speed when it emerges from the $P$-side?

$A$ semiconductor $X$ is made by doping a germanium crystal with indium $(Z = 49)$. $A$ second semiconductor $Y$ is made by doping germanium crystal with arsenic $(Z = 33)$. Both are joined end to end and connected to a battery as shown. Which of the following statements is correct?

The figure shows a circuit in which three identical diodes are used. Each diode has a forward resistance of $20\,\Omega$ and an infinite backward resistance. Resistors $R_1 = R_2 = R_3 = 50\,\Omega$. The battery voltage is $6\,V$. The current through $R_3$ is.....$mA$.

Explain the barrier potential and depletion region in a $p-n$ junction diode.

Statement $I :$ When a $Si$ sample is doped with Boron,it becomes $P$-type and when doped by Arsenic it becomes $N$-type semiconductor such that $P$-type has excess holes and $N$-type has excess electrons.
Statement $II$ : When such $P$-type and $N$-type semiconductors are fused to make a junction,a current will automatically flow which can be detected with an externally connected ammeter.
In the light of above statements,choose the most appropriate answer from the options given below.

For the forward biased diode characteristics shown in the figure,the dynamic resistance at $I_{D} = 3 \, \text{mA}$ will be $..... \, \Omega$.