For an $L E D$ to emit light in visible region of the electromagnetic spectrum, it can have energy band gap…
For an $L E D$ to emit light in visible region of the electromagnetic spectrum, it can have energy band gap in the range of, (Plank's constant, $h=6.6 \times 10^{-34} \mathrm{Js}$ and speed of light, $e=3 \times 10^8 \mathrm{~ms}^{-1}$ in vacuum)
0.1 eV to 0.4 eV
0.9 eV to 1.6 eV
1.7 eV to 3.1 eV
0.5 eV to 0.8 eV
Solution
Key Idea Frequency of visible rays range from $4 \times 10^{14} \mathrm{~Hz}$ to $7 \times 10^{14} \mathrm{~Hz}$.
Maximum and minimum energy of photon in visible light,
$
\begin{aligned}
E_{\max } & =h v=\frac{6.6 \times 10^{-34} \times 7 \times 10^{14}}{1.6 \times 10^{-19}} \\
& =2.88 \mathrm{eV} \simeq 3 \mathrm{eV} \\
E_{\min } & =\frac{6.6 \times 10^{-34} \times 4 \times 10^{14}}{1.6 \times 10^{-19}} \\
& =1.65 \mathrm{eV} \simeq 1.7 \mathrm{eV}
\end{aligned}
$
So, the correct option matches between the energy $1.7 \mathrm{eV}$ to $3 \mathrm{eV}$ is $(\mathrm{c})$