xl4. If the valence band energy of a certain material is 0.2ev, and the band gap
ID: 1613824 • Letter: X
Question
xl4. If the valence band energy of a certain material is 0.2ev, and the band gap energy is 1.2eV, what is the conduction band energy 17. The electron microscope my advisor uses accelerates electrons through a voltage of 400kv. which means the electrons have an energy of 6.408x10 J. is the What wavelength of these electrons? 18. If semiconductor that makes up a solar cell has a bandgap energy of 1.43ev. what wavelength of light will cause electrons to be excited from the valence band to the conduction band? 19. If you stand 3ft in front of a mirror and see your reflection 5ft behind the mimor, are you looking at a plane, concave, or convex mirror? Conca what is the wavelength of a photon if its i?ls this photon in energy is 1 the visible region of the spectrum?Explanation / Answer
16) Ev = 0.2 eV, Eg = 1.2 eV
Ec = 0.2+1.2 = 1.4 eV
17) K = 6.408*10^-14 J
lamda =h/p = h/(2mK)^0.5
lamda = 6.63*10^-34/(2*9.1*10^-31*6.408*10^-14)^0.5
lamda = 1.94*10^-12 m
18) E = 1.43 eV
E(eV) =1243/lamda(nm)
1.43 = 1243/lamda
lamda = 869 nm
19) from mirror formula
1/f = 1/s +1/s'
1/f = 1/3 -1/5
f = +7.5 ft
f is positive, so it is concave mirror
20) E = hc/lamda
1.55*10^-19 = 6.63*10^-34*3*10^8/lamda
lamda = 1.28 um
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