$A$ semiconductor device $X$ is connected in series with a battery and a resistor. $A$ current of $10 \ mA$ is found to pass through the circuit. If the terminals of $X$ are connected in reverse,the current drops to almost zero. $X$ may be

In the depletion layer of a reverse-biased $p-n$ junction,the

The forward biased diode connection is:

In a $P-N$ junction,the thickness of the depletion layer is $10^{-6} \ m$ and the potential barrier is $0.1 \ V$. The electric field in $V/m$ is:

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:

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