What is an example of a wavelength calculations practice problem?

1 Answer
Truong-Son N.
Nov 3, 2015

Chances are, if you work with wavelengths λ, you are probably going to see Planck's constant h, so let's try one of those problems.

Try calculating the energy of a single photon of a particular wavelength.

Ephoton=hν=hcλ

... if its wavelength is red (let's say the wavelength was 600 nm). The speed of light is about 2.998×108m/s and h=6.626×10−34J⋅s.

Here's a hint for your units: J=kg⋅m2/s2. What do you need to do to get to J by operating with J⋅s, m, and nm−1?

You should get 3.31079×10−19J.

(If you get 3.31079×10−17J, check your wavelength. 600 nm≠6×10−9m.)

CHALLENGE: See if you can convert the energy here from J to cm−1. Hint: c=3×1010cm/s, and consider the only equation given above.

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