Using E = hc/λ to Calculate Energy of a Wave (Example 4)

In this video, we find the energy associated with a radio wave given its frequency by first calculating its wavelength (through λ = c/f) and then using our calculated wavelength in E = hc/λ to find the energy.
If you went further and converted the answer from eV into joules, you should have gotten an answer of E = 1.8 x 10^-26 J.
Of course, you may forego the steps shown in this video if you replace the c/λ with f in the original equation E = hc/λ instead. This will give you E = hf, and now you have to multiply Planck's constant with the frequency of the wave, which is doable too and should give you E = 1.324 x 10^-26 J.
There is a small discrepancy in the calculated values for energy E that arises from our use of hc = 1240 eV nm in the example shown in the video. If we used hc = 1241.25 eV nm (its unrounded value), then we'll get E = 1.324 x 10^-26 J, regardless of which method was used.
The content in this video was designed and created for Anoush Kazarians' Astro 110: Astronomy of the Solar System course at Glendale Community College (Glendale, CA).

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