Units

[305670352]

when converting an answer from nm to m, does the calculation need to be done when the value is a unit of distance (wavelength), or can the conversion (x10^-9) be made at the end when the value is no longer representing a distance?

Might be as stupid question as I thought it makes no difference, but my answer is showing incorrect and im otherwise not sure why

[Josh Richter 2C]

nm stands for nanometers, which inherently is a unit of distance that represents 10^-9 meters. So in that sense, if you are ever working nanometers, it will always represent a distance. However, when doing problems with wavelength, I like to always use SI units first. If the problems give me a distance in nanometers, I will convert to meters if I'm trying to find something like the frequency of electromagnetic radiation. Also, the nano prefix isn't just specific to meters, it just represents one-billionth of whatever unit it is in front of.

[Tess_Fleser_1D]

If you are multiplying by the wavelength then in theory it shouldn't make a difference if you do it at the beginning vs at the end. If you are dividing by the wavelength than it would definitely cause some issues.

I would say it is probably always safer to convert to SI base units before you start calculations, especially for longer and more complex equations.

[N Kanuri 2E]

I would recommend converting units in the appropriate step, when you are still dealing with distance - this makes your work much clearer and eliminates the possibility of making a mistake in the end. I hope this helps!

[Miranda Hess 3I]

Yeah as was already said, you could technically pull off doing the conversion at the end on a few cases by dividing at the end, but this really only applies to calculations that don't get too complex. Why would you want to do that if it only works in a few, hard to distinguish cases? Doing it first means that your calculations will make sense from the very beginning and you don't risk anything.

[Jessica Arcos 2H]

I think it would be better to convert units before you start a problem just so that you don't get mixed up with your calculations.

[gwenkelley3L]

Regardless of whether it yields the right answer or not, it will probably be easier to just convert from the beginning, so your numbers will always be accurate and you will be less likely to get confused with you work!

[Nishan Reddy 3K]

nm stands for nanometer and the nano- prefix refers to 10^-9 of the base unit in the metric system. So that it can refer to 10^-9 liters, grams, meters, etc.. Make sure however that you use the correct units that match the units used in various constants / equations.

[Brianna Mercado 3D]

hello, I was having similar problems when converting, its easiest to convert when initially starting your problem so you don't get slight conversion mistakes

[SheaZenker_3F]

especially, it will be easier to identify the incorrect units at the beginning of problems, so I would suggest not waiting until later in case you forget.

[205793570]

Hi, I personally do it at the very end, it has been working for me to use the 1x10^-9 when the entire calculation is done.

[Daniela G 2C]

I have seen the conversion be done at the end, but personally, to avoid any mistakes I convert when the value is still in units of distance. There have been some problems (like my answer is off) when I don't convert nm to m when it is necessary, so just to be safe converting to the appropriate unit of measure should be done before.

[305597516]

I feel like it would just be easier to convert when it is a distance (typically the first thing I do in a problem is convert units to the question's desired units). When it is no longer a distance (like for example if you had nm/s), it can be possible if distance is still a component, although this will require the work of converting the time units (or whatever else is there) instead.

[JasmineReyes-2K]

Try converting units when you are still dealing with distance, this honestly helped me so much :)