Question
Do the unit conversions necessary to show that hc=1240 eVnmhc = 1240\textrm{ eV}\cdot\textrm{nm}, as stated in the text.
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OpenStax College Physics, Chapter 29, Problem 24 (Problems & Exercises)

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Video Transcript
This is College Physics Answers with Shaun Dychko. We are going to verify that Planck's constant times the speed of light can be written as 1240 electron volt nanometers and I use this version for Planck's constant times speed of light quite often because it's convenient in many of our problems. So Planck's constant is 6.626 times 10 to the minus 34 joules seconds if we write these units in mks units— meters, kilograms and seconds— and the speed of light is 2.998 times 10 to the 8 meters per second. Let's do one of our conversions in this line here let's convert these joules into electron volts by multiplying by 1 electron volt for every 1.602 times 10 to the minus 19 joules and this second cancels with the second in the denominator of the units for the speed and we are left with electron volt meters in our answer to that so that's 1.23999675 times 10 to the minus 6 electron volt meters and then we'll convert the meters into nanometers by multiplying by 10 to the 9 nanometers for every meter and we end up with the answer of 1240 electron volt nanometers.