Companion cells are closely associated with $..........$.

$A$ $p-n$ photodiode is made of a material with a band gap of $2.0 \text{ eV}$. The minimum frequency of the radiation that can be absorbed by the material is nearly

$\frac{\sqrt{5/2} + \sqrt{7 - 3\sqrt{5}}}{\sqrt{7/2} + \sqrt{16 - 5\sqrt{7}}} = ?$

$A$ ray of light strikes a plane mirror $M$ at an angle of $45^o$ as shown in the figure. After reflection,the ray passes through a prism of refractive index $1.5$ whose apex angle is $4^o$. The total angle through which the ray is deviated is....$^o$

Which of the following is an opiate narcotic?

The number of $p\pi-d\pi$ 'pi' bonds present in $XeO_3$ and $XeO_4$ molecules,respectively,are: