$A$ $PN-$ junction has a thickness of the order of

In a $PN-$junction diode:

For a diode connected in parallel with a resistor,which is the most likely current $I$-voltage $V$ characteristic?

The energy of a photon in a monochromatic light of wavelength $621 \ nm$ matches with the band gap of a semiconducting material. Then the minimum energy required to create an electron-hole pair from the semiconductor is
[Take $hc = 1242 \ eV-nm$,where $h$ is Planck's constant and $c$ is speed of light in vacuum] (in $eV$)

Consider a circuit consisting of a capacitor $(20 \mu\text{F})$,a resistor $(100 \Omega)$,and two identical diodes as shown in the figure. The resistance of each diode under forward biasing condition is $10 \Omega$. The time constant of the circuit is $\alpha \times 10^{-3} \text{ s}$. The value of $\alpha$ is . . . . . . .

If the $p-n$ junction diode is unbiased,