Energy of Light

Question

The energy of a particular color of violet light is 4.51×10^-22 kJ/photon.

The wavelength of this light is ______nanometers.

(10⁹ nm = 1 m)

Answer 1

The energy of a photon is given by

E = hc./λ where h is Planck's constant (6.626 x 10^-34) J-s, c is the speed of light (3.00 x 10⁸) m/s, and λ is the wavelength.

Solve for λ to get λ = hc/E. Convert E to Joules and obtain E = 4.51 x 10^-19 J

λ = 6.626 x 10^-34 Js x 3.00 x 10⁸ m/s / 4.51 x 10^-19 J x 10⁹ nm/1m = 441 nm