The material suitable for making a solar cell is

Explain the design,working,uses,and benefits of a light-emitting diode $(LED)$.

Which of the following statements is not correct in the case of light emitting diodes?

To measure light intensity,we use:

The semiconductor used for the fabrication of visible LEDs must at least have a band gap of (in $eV$)

For three circuit elements $A, B$ and $C$,following observations were made in lab:
$(a)$ element $A$ cannot conduct $d.c.$ but allows $a.c.$ through it.
$(b)$ element $B$ conducts both $AC$ and $DC$ but in one direction only.
$(c)$ Element $C$,when connected across $DC$,conducts only for one polarity and emits light whose intensity first increases and then decreases with increase in applied voltage.
The elements $A, B$ and $C$ are respectively identified as