In forward bias,the width of the potential barrier in a $P-N$ junction diode:

Among the diodes shown in the following diagrams,which one is reverse biased?

$A$ $2\,V$ battery is connected across $AB$ as shown in the figure. The value of the current supplied by the battery when in one case the battery's positive terminal is connected to $A$ and in the other case when the positive terminal of the battery is connected to $B$ will respectively be:

In the figure shown, if the diode forward voltage drop is $0.2 \, V$, the voltage difference between $A$ and $B$ is (in $V$)

$A$ crystal diode is a:

Refer to the circuit diagram given in the figure. Which of the following observations are correct?
$A.$ Total resistance of the circuit is $6 \ \Omega$.
$B.$ Current in the ammeter is $1 \ A$.
$C.$ Potential across $AB$ is $4 \ V$.
$D.$ Potential across $CD$ is $4 \ V$.
$E.$ Total resistance of the circuit is $8 \ \Omega$.
Choose the correct answer from the options given below: