For LED's to emit light in visible region of electromagnetic light, it should have energy band gap in the…
For LED's to emit light in visible region of electromagnetic light, it should have energy band gap in the range of:
-
$0.1 \mathrm{eV}$ to $0.4 \mathrm{eV}$
-
$0.5 \mathrm{eV}$ to $0.8 \mathrm{eV}$
-
$0.9 \mathrm{eV}$ to $1.6 \mathrm{eV}$
-
$1.7 \mathrm{eV}$ to $3.0 \mathrm{eV}$
Solution
Energy band gap range is given by,
$
\mathrm{E}_{\mathrm{g}}=\frac{\mathrm{hc}}{\lambda}
$
For visible region
$
\begin{aligned}
&\lambda=\left(4 \times 10^{-7} \sim 7 \times 10^{-7}\right) \mathrm{m} \\
&\mathrm{E}_{\mathrm{g}}=\frac{6.6 \times 10^{-34} \times 3 \times 10^8}{7 \times 10^{-7}} \\
&=\frac{19.8 \times 10^{-26}}{7 \times 10^{-7}} \\
&=\frac{2.8 \times 10^{-19}}{1.6 \times 10^{-19}} \\
&\mathrm{E}_{\mathrm{g}}=1.75 \mathrm{eV}
\end{aligned}
$
Asked in: JEE Main 2014 (12 Apr Online)
Practice more Dual Nature of Matter questions on Aicharya