Chapter 12, Problem 43AP

Interpretation Introduction

Interpretation:

The larger band-gapof semiconductors, whether of a green exit sign’s LEDs or of red traffic signal, is to be determined.

Concept introduction:

Semiconductors are the solids thathave a conductivity between that of conductors and insulators.

The gap between the conduction band and the valence band is small, so electrons may jump from the valence band to the conduction band.

$E=\frac{hc}{\lambda }$, where E is the energy and $\lambda$ is wavelength.

Energy is inversely proportional to wavelength. Hence, light with shorter wavelength have high energy and light with longer wavelength have low energy.