Which one of the following symbols represents a photodiode?

Describe the construction, working, and use of a solar cell.

The energy band gap of a semiconducting material required to produce a violet (wavelength $= 4000 \, \mathring{A}$) $LED$ is $....... \, \text{eV}$. (Round off to the nearest integer).

Which of the following statements is true about LEDs?

To measure light intensity,we use:

$A$ $CCD$ camera is fabricated using a semiconducting material having a band gap of $3 \ eV$. The wavelength of light it can detect is nearly (in $nm$)