What is the energy of photon whose wavelength is `6840 Å` ?

Options

A. `1.81 eV
B. 3.6 eV
C. `-13.6 eV
D. 12.1 eV

Answer

A

Explanation

`lambda = 6840 Å`
`therefore upsilon =(c )/(lambda) rArr h upsilon = (hc)/(lambda), hc = 12400 eV Å`
Energy of the photon `=(12400 eV Å)/(6840 Å)=1.81 Å`