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I'm confused on whether we use nm or m when we have wavelength in an equation. I assumed it was nm since Lavelle gave us the wavelengths of the visible light spectrum in nm, however when I was working on the homework this week, my answer was incorrect because I used nm instead of converting it to m. Can anyone help?
You have to use meters because the other values are are in meters and ultimately, the units need to cancel. For example, the speed of light is 3.00E8 m/s. To make sure the units cancel in the equation , you would need your wavelength in meters as well, since the frequency is in Hz, or s^-1.
Hope this helps!
Hope this helps!
Usually in the equations, you have to use whatever units the constants have in order to cancel them out. For example, Joules are kg·m^2·s^-2, so when there's Joules in the equation (Plank's constant), you need to use kg, meters, and seconds. However, sometimes the question will ask you to convert from m to nm after you have solved for an answer.
Hi! Wavelength is usually measured in m, which is one of the basic SI units. Constants such as the speed of light (3.0 x 10^8 m.s-1) and Planck's constant (6.626x10^-34 kg.m^2.S^-2) are given in units of meters; therefore, in order for the units of the values to cancel out with each other during calculations, the unit m must be used. Hope this helps! :)
Hello, so everyone who has answered meters above is absolutely correct. I would like to add a small explanation as to why the professor gives the answers in nm. So, he has said in lecture before that it is for convenience. Saying something like 178 nanometers is easier than having a mouthful of 1.78 *10^-10 m . The calculations that you go through have to be in meters that way your units cancel according to SI units, but for the purpose of convenient reporting sometimes it is easier to give the answer in nm rather than m.
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