For an infinitesimally small dipole in free space, the electric field $E_\theta$ in the far field is proportional to $\frac{e^{-j k r}}{r} \sin \theta$, where $k=\frac{2 \pi}{\lambda}$. A vertical infinitesimally small electric dipole ( $\delta l \ll \lambda$ ) is placed at a distance $h(h>0)$ above an infinite ideal conducting plane, as shown in the figure. The minimum value of $h$, for which one of the maxima in the far field radiation pattern occurs at $\theta=60^{\circ}$, is

Consider the recombination process via bulk traps in a forward biased $p n$ homojunction diode. The maximum recombination rate is $U_{\max }$. If the electron and the hole capture cross sections are equal, which one of the following is FALSE?

A single crystal intrinsic semiconductor is at a temperature of 300 K with effective density of states for holes twice that of electrons. The thermal voltage is 26 mV . The intrinsic Fermi level is shifted from midbandgap energy level by

A $p n$ junction solar cell of area $1.0 \mathrm{~cm}^2$, illuminated uniformly with $100 \mathrm{mWcm}^{-2}$; has the following parameter : Efficiency $=15 \%$, open circuit voltage $=0.7 \mathrm{~V}$, fill factor $=0.8$, and thickness $=200 \mu \mathrm{~m}$. The charge of an electron is $1.6 \times 10^{-19} \mathrm{C}$. The average optical generation rate ( $\mathrm{in} \mathrm{cm}^{-3} \mathrm{~s}^{-1}$ ) is