Energy of Light

Question

X-ray radiation falls in the wavelength region of 1.00×10^-11 to 1.00×10^-8 meters.

What is the energy of X-ray radiation that has a wavelength of 1.00×10^-11 m?

Energy =  _______kJ/photon

Answer 1

The two equations we need when dealing with energy of light are:

E = hν where E = energy of a photon of light; h = Planck's constant (see below) and ν = frequency in Hz

c = λν where c = speed of light (~3x10⁸ m/sec), λ= wavelength in m and ν = frequency in Hz

Rearranging these two equations, we end up with

E = hc/λ which is the equation we shall use to solve the current problem.

E = ?

h = 6.626x10^-34 Jsec

c = 3x10⁸ m/sec

λ = 1.00x10^-11 m

E = (6.626x10^-34 Jsec)(3x10⁸ m/sec) / 1.00x10^-11 m

E = 1.99x10^-14 J/photon x 1 kJ/10³ J = 1.99x10^-17 kJ/photon