Chemistry/Physics Question

Question

What is the energy of a photon with a frequency of 280 GHz?

Answer 1

Photon energy is calculated using Planck's postulate which is written as E = hf, where E is photon energy in Joules; h is Planck's constant (6.626x10^-34 Joule seconds); and f is the frequency of the light in hertz.

The frequency of 280 GHz is 280x10^9 Hz.= 280x10^9 sec^-1

So E = (6.626x10^-34 Joule seconds)(280x10^9 sec^-1) = 1,855x10^-22 joules, Rounding this to 2 sig figs gives E = 1.9x10-22 joules

Answer 2

For this problem, there are a few things you have to know.

1.) The conversion factor of Hertz, or Hz. Hertx is defined as one cycle per second or 1/s.

2.) The conversion factor for the unit prefix Giga. This unit prefix is equal to 1.0 x 10⁹.

3.) The equation E = hv where E is a single quantum of energy, h is Planchk's constant and has a value of 6.63 x 10^{- 34} Js.

Given this information, the problem is solved by canceling out units given the equation.

E = hv = 6.63 x 10^{- 34} Js x 280 x 10⁹ 1/s = 1.85 x 10^-22 J

The energy of a photon with the frequency of 280 GHz will be 1.85 x 10^-22 J.