Find the band gap energy when a light of wavelength 1240nm is incident on it.

The band gap energy of a material can be determined when light of a certain wavelength is incident on it using the equation:

[ E = frac{hc}{lambda} ]

where:

– (E) is the band gap energy in electron volts (eV),

– (h) is Planck’s constant ((6.626 times 10^{-34}) m(^2)kg/s),

– (c) is the speed of light in vacuum ((3.00 times 10^8) m/s),

– (lambda) is the wavelength of the incident light in meters.

Given:

– Wavelength (lambda = 1240) nm = (1240 times 10^{-9}) m (since (1) nm = (10^{-9}) m)

First, convert constants and given values to compatible units (if necessary, but they are already compatible in our case), and then use the equation to find (E).

[ E = frac{(6.626 times 10^{-34}, text{m}^2text{kg/s})(3.00 times 10^8, text{m/s})}{1240 times 10^{-9}, text{m}} ]

[ E = frac{1.9878 times 10^{-25}, text{m}^2text{kg/s}}{124