Answer:
The energy gap of the material is [tex]E_G = 1.7982 eV[/tex]
Explanation:
From the question we are told that
The wavelength is [tex]\lambda = 690 nm[/tex]
The band gap of the material can be mathematically represented as
[tex]E_G = \frac{h c}{\lambda }[/tex]
Where h is the Planck constant with value [tex]h = 6.626 *10^{-34} joule \cdot sec[/tex]
c is the speed of light with a value [tex]c = 3.0*10^8[/tex]
Substituting value
[tex]E_G =\frac{6.626 *10^{-34} 3 *10^{8}}{690 *10^{-9}}[/tex]
[tex]= 2.8809 *10^{-19}J[/tex]
Now converting to eV we divide by the charge on on electron. the value is
[tex]e = 1.602 *10^{-19 } C[/tex]
so
[tex]E_G = \frac{2..8809 *10^{-19}}{1.602 *10^{-19}}[/tex]
[tex]E_G = 1.7982 eV[/tex]
