What are the photon energies corresponding to the following wavelengths?
E (in eV) =
Near IR, 1000 nm
Far red end of the spectrum, 750 nm
Far blue end of the spectrum, 400 nm
Near UV, 290 nm
= eσAT 4
σ = 5.67 x 10 W/(m K ) 4
Visible spectrum: approx.. 400 – 750 nm
Peak intensity shifts to shorter wavelengths as the temperature increases.
λpeak(in nm) = T
Wien’s law for the peak wavelength of a thermal emission spectrum
A typical incandescent lamp has a filament at a temperature of approximately 2500 °C.
What is the peak wavelength of the emission?
Temp in K = 2500 + 273 = 2773 K
2773K 980 nm
Visible Light, Near IR and UV
The three different types of cones have different color sensitivities.
The band gap of the silicon used to make the CCD detector in a black and white security
camera is 1.12 eV. Photons with energy greater than this will be detected.
What wavelength does this correspond to?
1.12 eV = λ