A photon of light has an energy of 1.67 x 10-17 J. What is the frequency (Hz) of this light wave? E= hv

Answer 1

For this problem you are going to use Planck's Equation: E = hv

Where:

E = energy (in Joules)

h = Planck's Constant (6.63 x 10^-34 Js)

v = frequency (s^-1 or hertz, where 1 Hz = 1 s^-1)

You are given the value for energy, you should also be familiar with Planck's constant. You can rewrite the equation to solve for frequency and plug in the given values to solve for v:

v = E / h

v = (1.67 x 10^-17 Joules) / (6.63 x 10^-34 Js) = 2.5189 x 10¹⁶ s^-1

which can be expressed as: 2.5189 x 10¹⁶ Hz (since 1 Hz = 1 s^-1)

Side note: frequency is expressed in inverse seconds (s^-1 = 1/s) because the unit for seconds is in the denominator of the equation. When doing the calculation, the unit for Joules will cancel out because you are dividing joules by joules x s, which leaves you with your answer expressed in inverse seconds.

Another helpful hint: if you are unsure if your answer for frequency is correct. You can substitute the answer you got for frequency back into the original energy equation (E = hv), and multiply it by Planck's constant. If your answer for frequency is correct, you should get 1.67 x 10^-17 J as your answer for energy.

I hope this helps! Please leave feedback or leave a comment if you have any questions or need further clarification.