CHEMISTRY COMMUNITY

Posted: **Wed Oct 14, 2020 11:12 am**

On the test, will we need to format our answers in meters or nanometers when solving for wavelength?

Posted: **Wed Oct 14, 2020 11:15 am**

If the question specifically asks for nm, then convert to nm. If the question does not specify anything, Dr. Lavelle mentioned in today's lecture that it's fine to keep an answer in meters, so I'm assuming this also applies to tests.

Posted: **Wed Oct 14, 2020 11:15 am**

Normally the question specifies if it wants to wavelength in nanometers. If it doesn't specify, then I assume meters should be fine. Otherwise, it doesn't hurt to write it in both meters and nanometers :)

Posted: **Wed Oct 14, 2020 12:22 pm**

I don't think it's necessary if it doesn't specify converting the final answer in nm. However, the wavelength is usually referred to in nm so it might be of benefit to get in the habit of doing the conversion.

Posted: **Wed Oct 14, 2020 1:06 pm**

I do not think there is a specific unit to use unless it is stated in the question. As long as the conversion from m to nm is correct, you should be fine. :)

Posted: **Wed Oct 14, 2020 1:28 pm**

When solving for wavelength it would most likely specify what format the answer should be in. If you are not told whether it has to be in meters or nanometers, it should be fine to have your answer in meters.

Posted: **Wed Oct 14, 2020 5:32 pm**

The difference between m and nm is usually that when solving for wavelength your result would be an answer similar to (for example), (7.14 x 10^-7)m. I have noticed that it is usually 10^-7m and since nm = 10^-9, the only thing you have to do to convert is move the decimal over two more spaces to the right and the result would be 714 nm. The conversion is really simple. It is not necessary (unless it is multiple choice, so you should know how) but it is recommended because it is more well used in the quantum field.

Posted: **Wed Oct 14, 2020 9:59 pm**

Based on today's lecture #6, Dr. Lavelle worked a problem and said that you could leave your answers in nanometers or meters; both are acceptable. But, it is easier to just say nanometers for an answer if it is x10^-9.

Posted: **Wed Oct 14, 2020 10:04 pm**

Unless the problem states otherwise, I think both forms are acceptable. They just need to be the correct value. I would just make sure on the test to use the correct unit if it specifies in the problem.

Posted: **Wed Oct 14, 2020 10:37 pm**

Dr. Lavelle informed us that it is alright to leave your answers in meters. However, if the question specifically asks for nanometers, then convert it :)

Posted: **Wed Oct 14, 2020 10:40 pm**

The SI unit for length is meters so when in doubt I would go with that! But in an example problem during lecture, Professor said that both meters and nanometers are acceptable. Unless explicitly specified or needed for specific conversion factors both should work:)

Posted: **Thu Oct 15, 2020 7:18 am**

The formula you use in the calculations can also give you an idea of which to use. For instance, in the equation c=lambda*v, the units for the speed of light is meters per second so you would want the unit of lambda to be meters as the units of v is s^-1.

Posted: **Thu Oct 15, 2020 9:28 am**

I don't think it matters which one you use as long as they are the correct conversion. nanometers is a much more readable number so I prefer using nm.

Posted: **Thu Oct 15, 2020 11:06 am**

In the lecture, Dr. Lavelle said you can leave your answer in meters. However, in my discussion, my TA converted all those values to nanometers because the electromagnetic spectrum has wavelengths measured in nanometers. Sometimes it is helpful to make this conversion. Unless it is directly specified, however, it is not necessary to convert meters to nanometers.

Posted: **Thu Oct 15, 2020 11:09 am**

All of these replies are correct, but I just want to add on a note to keep in kind. When dealing with equations like (wavelength)(frequency) = c, make sure that wavelength is in meters, as that's the si unit that is used in this calculation. Other than that, yes, your answer can either be in m or nm depending on the context of the question!

Posted: **Thu Oct 15, 2020 11:53 pm**

I prefer to put the answer in nanometers since it just easier to read rather rather than reading it in meters way past the decimal.

Posted: **Fri Oct 16, 2020 12:36 am**

If the question does not specify the units your answer should be in, then it shouldn't matter whether you answer with m or nm.

Posted: **Fri Oct 16, 2020 1:03 am**

Like others have said, it's not really important to convert the final answers all the way to nanometers. The biggest thing would be to remember that the formulas for frequency are calculated in meters, so that there wouldn't be a slip-up and writing down something like "1.56*10^-7 nanometers"

Posted: **Fri Oct 16, 2020 3:54 pm**

Maya Johnson 1c wrote:On the test, will we need to format our answers in meters or nanometers when solving for wavelength?

It'll definitely depend on the question (whether it asks for a certain unit or not). Otherwise, I think answering in meters isn't wrong. It's just that often times the wavelengths are usually done in nanometers so converting to nanometers might make it easier for reading.

Posted: **Fri Oct 16, 2020 4:54 pm**

I'm pretty sure it will specify what kind of SI units it will want, just know that NM is 10^-9 units.

Posted: **Fri Oct 16, 2020 4:59 pm**

It definitely depends on the question, but if it doesn't specifically state what units to use, I think it would be okay to stick with meters.

Posted: **Fri Oct 16, 2020 8:51 pm**

Generally, as for wavelength, we use "nm" nanometers.

Posted: **Sat Oct 17, 2020 2:17 pm**

Either should be fine as long as the conversions are done correctly, but personally I prefer to use nm in my final answer.

Posted: **Sat Oct 17, 2020 3:47 pm**

Meters is usually best, but nano meters works just as well for the final answer. You just have to make sure you're using scientific notation properly and you convert. Either works but more importantly focus on converting correctly.

Posted: **Sat Oct 17, 2020 4:32 pm**

Unless specified otherwise, both units would be acceptable since m is the SI unit for length and nm is the common unit for wavelength. But if you want to be safe, you could also just write both units since it's a fairly quick and easy conversion.

Posted: **Sat Oct 17, 2020 4:59 pm**

Usually the SI unit for the wavelength that comes from the speed of light formula is in m. However, for most of the questions, I've found they want the answer to be in nm. When going to from m to nm, multiply by 1E9 and from nm to m multiply 1E-9.

Posted: **Sat Oct 17, 2020 6:11 pm**

Either should be acceptable but often converting the final answer of m to nm is best/makes the most sense. Just make sure if it asks specifically for nm you give the answer with that measure.

Posted: **Sat Oct 17, 2020 6:57 pm**

I think that if the question specifically asks for nm, then it's best practice to put the answer in nm. If not, I think either will work!

Posted: **Sat Oct 17, 2020 7:42 pm**

It does not matter which unit you should use unless the problem specifically states so to use a specific unit. I believe that keeping your answer in meters should be fine for the most part.

Posted: **Sat Oct 17, 2020 7:56 pm**

I believe that as long as your answer is still accurate, it can in either meters or nanometers, unless explicitly stated otherwise. My TA said the preferred version is for it to be in nanometers, but leaving it in meters is also acceptable. It just comes down to it looking nicer and concise when the answer is formatted in nanometers.

Posted: **Sat Oct 17, 2020 8:35 pm**

My TA said that it doesn't matter, but wavelength is typically expressed in nanometers which is why they prefer wavelength to be in units of nm!

Posted: **Sat Oct 17, 2020 9:29 pm**

In one of the lectures, it was mentioned that wavelength is usually expressed in nm. However, it can depend on the question being asked. The question will usually specify how to express your answer.

Posted: **Sun Oct 18, 2020 12:01 am**

It seems as if either nanometers or meters are acceptable as long as the question does not specify which SI units are required for answering the question.

Posted: **Sun Oct 18, 2020 10:17 am**

I think that if the question doesn't specify particular units of measurement, then both should be fine as they have equal values. Just remember to use the correct scientific notation nm= 10^-9
Also, round to the correct significant figures to not have any inconsistencies!

Posted: **Sun Oct 18, 2020 10:23 am**

I believe that we answer in meters (m) because that is the SI units for distance, however, if the question asks for the answer in different units (ie. nanometers (nm) or picometers (pm)) then you will have to convert it. But in general, it's best to leave the units as meters.

I do think there are some times when he converts answers to different units like 0.134 L to 134 mL. But I think its safer to just leave your answer in SI units!

Posted: **Sun Oct 18, 2020 2:34 pm**

I will assume that as long as the problem does not specify, we can use which ever makes more sense in the context of the problem. For me personally I like to use nm only for wavelength that are in or fairly close to the visible region. Also most of the questions will be online in form of multiple choice, the unit should not be a problem.

Posted: **Sun Oct 18, 2020 2:36 pm**

If the question asks, then I assume that you would need to convert to nm. However, if it doesn't mention anything Lavelle said that meters will work in the solution.

Posted: **Sun Oct 18, 2020 3:18 pm**

Hi! I believe either is fine, unless the question specifically asks for one over the other. As others have said, though, I think many of the test questions will be multiple choice, so it might not be an issue at all.

Posted: **Sun Oct 18, 2020 5:05 pm**

The test should specify what units the answer should be in. If not meters is most likely okay.

Posted: **Sun Oct 18, 2020 8:33 pm**

I believe it depends on what you are trying to calculate and what it is asking for. For the most part, it will probably ask for nanometers.

Posted: **Sun Oct 18, 2020 8:40 pm**

From what I can understand, it depends on the question and if it does not specify then it comes to your judgement and knowledge of chemistry on what would look more appropriate.

Posted: **Sun Oct 18, 2020 9:00 pm**

Lavelle mentioned in the lecture that it's acceptable to leave the answer in meters. I'm assuming that this also applies to exams.

Posted: **Sun Oct 18, 2020 9:26 pm**

The test'll be in multiple choice anyway, but you'd adjust the answer to match the question.

eg.) How many nm does the electron travel?
answer: ____nm

eg.) How many m does the electron travel?
answer: ____m

Posted: **Sun Oct 18, 2020 9:32 pm**

I asked my PLF a similar question and she explained that if needed to 1) it'll explicitly tell us and 2) in the past, he's given a sheet with formulas and we can refer to it. I'm not sure how that's going to work with the test being online though.

Posted: **Sun Oct 18, 2020 10:12 pm**

I believe that leaving your answer in either nanometers or meters is fine but wavelength is usually expressed in nm. Ususally the question will specify what units your answer should be in.

Posted: **Sun Oct 18, 2020 10:28 pm**

When wavelength is used in the formulas, you typically need it in meters so that units cancel out. I'm sure that there will be questions (like the one on the practice quiz we took) where you get wavelength in nm and need to put it in m before you plug in. As long as you memorize the conversion, you won't have to worry too much. You'll easily be able to go back and forth as needed. As far as answering the question in m and nm, I imagine that either nm or m is fine (unless otherwise specified).

Posted: **Sun Oct 18, 2020 10:31 pm**

Unless specified, its ok to write in either format

Posted: **Sun Oct 18, 2020 10:33 pm**

I think its usually written as nm but either is fine

Posted: **Sun Oct 18, 2020 10:53 pm**

I am pretty sure it will specify, if not nm is probably the one to use.

Posted: **Thu Oct 22, 2020 5:52 pm**

I don't think its a huge deal and the midterm is likely multiple choice, which means the answer choices will show you what to convert to.

Posted: **Thu Oct 22, 2020 9:57 pm**

I think both are OK, unless it is stated in the question.

Posted: **Thu Oct 22, 2020 10:04 pm**

Wavelength values are usually given in nm but if the question says to give the answer in m then you should give it in m.

Posted: **Fri Oct 23, 2020 1:40 pm**

The midterm is multiple choice and they aren't collecting scratch work, so is doesn't matter if it's in m or nm, as long as it's correct.

Posted: **Fri Oct 23, 2020 2:02 pm**

No, not unless specified in the question.

Posted: **Fri Oct 23, 2020 7:45 pm**

When doing calculations, I believe the quantities are supposed to be written in meters! However, since the midterm is multiple choice, you'll be able to see if the final answer is going to be m or nm.

Posted: **Fri Oct 23, 2020 9:10 pm**

Usually the final answer should in nm? It's just in the problem the wavelength comes out be in m initially.

Posted: **Fri Oct 23, 2020 9:21 pm**

I think both ways are fine, it is a matter of units.

Posted: **Sat Oct 24, 2020 10:49 pm**

The questions will probably specify which unit to use! I believe the exam is also multiple choice, so you can tell that way too.

Posted: **Sat Oct 24, 2020 10:52 pm**

I believe either unit is fine unless specified by the question.

Posted: **Sun Oct 25, 2020 11:29 am**

Dr Lavelle said in lecture that unless the question specifically specifies that your answer should be in nm then it is fine to leave it in meters.

Posted: **Sun Oct 25, 2020 4:52 pm**

If I remember correctly, Lavelle mentioned that either unit is fine for a general answer. However, if a question asks for something concerning a wavelength, it is best to convert the units to nanometers (nm) as wavelength is given in that unit.

Posted: **Sun Oct 25, 2020 5:01 pm**

I believe the midterm is going to be multiple choice, so I guess it will depend on each individual question to see which unit the answers are in. I would just make sure you are comfortable converting between them so you don't get mixed up when looking for your answer or making a small error in the conversion and selecting an incorrect choice.

Posted: **Sun Oct 25, 2020 5:09 pm**

The question will most likely ask for specific units. Dr Lavelle has said either is fine unless specified.

Posted: **Sun Oct 25, 2020 5:24 pm**

Check the question, it will most likely tell you which units your answer should be in. But make sure when you are doing your calculations that you are using the standard meters for it, and only cover to nm after you have finished your calculations.

Posted: **Sun Oct 25, 2020 5:43 pm**

Since the exam will be multiple choice I would look at the units offered through the answers, if its in nm then just convert the answer found in m to nm if necessary.

Posted: **Mon Oct 26, 2020 1:37 am**

I agree with everyone that as long as conversion is correct, you're fine.
But if the unit for the anwser is already implied in the question, do what the question asks.

Posted: **Mon Oct 26, 2020 8:45 am**

I think always go with meters and then if they ask for it in nanometers, convert to nanometers if you have to but AFTER YOU HAVE CALCULATED THE ANSWER IN METERS because meters is the SI unit for length and is used for the speed of light constant.

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