## Units for wavelength/frequency

$c=\lambda v$

Bethany Yang 2E
Posts: 70
Joined: Wed Sep 30, 2020 9:39 pm

### Units for wavelength/frequency

Can someone clarify what units wavelengths and frequency are usually measured in? Also do you think on the midterm if the question does not specifically say, for example, " state the wavelength in nanometers", could you leave it in the unit that is not commonly used, and get full points?

Kailani_Dial_2K
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### Re: Units for wavelength/frequency

The units for wavelength is meters. the units for frequency is Hz which is also known as S^-1. The test will be multiple choice, so if it asks for it in nanometers then the answers should be given as nanometers as the options. They may try to trip you up and give you answers in meters when its not supposed to be so I would be weary of your units.

Megan Hulsy 1A
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Joined: Wed Sep 30, 2020 9:51 pm

### Re: Units for wavelength/frequency

Usually wavelength is mentioned in nanometers, but I believe the multiple choice options will be able to describe what units we'll have to use on the midterm for our answers.

Becca Nelson 3F
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Joined: Wed Sep 30, 2020 9:52 pm

### Re: Units for wavelength/frequency

Wavelength can be measured in many different quantities, but in formulas you should use meters. Through the sapling hw, I have seen nm, m and angstrom. When you see these different notations, just adjust the scientific notation accordingly.

Lorraine Medina 3E
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### Re: Units for wavelength/frequency

I think wavelength is usually in meters, so I would continue using meters when solving and then maybe converting at the end if they ask for any other units.

Neha Gupta 2A
Posts: 59
Joined: Wed Sep 30, 2020 9:52 pm

### Re: Units for wavelength/frequency

Hi there! Frequency is measured in Hz, aka 1/s. Wavelength is usually in meters but keep an eye out for nanometers because I've been seeing a lot of questions asking for nanometers instead of meters. It's usually best to convert from meters to nanometers at the end.

Evelyn Silva 3J
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Joined: Wed Sep 30, 2020 9:42 pm

### Re: Units for wavelength/frequency

When you're doing your calculations you should use meters for wavelength and Hz (s^-1) for frequency. However, if a problem specifies to give your answer in a specific unit then you would change it at the end.

Moura Girgis 1F
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Joined: Wed Sep 30, 2020 10:00 pm

### Re: Units for wavelength/frequency

The units for wavelength is in meters, and the units for frequency is in Hz, or s^-1. Since the midterm is multiple choice, the only thing you should worry about in terms of units is being able to convert if it is given in any other unit, such as nanometers instead of meters.

Isabella Cortes 2H
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Joined: Wed Sep 30, 2020 9:37 pm

### Re: Units for wavelength/frequency

HI!! wavelength is measured in meters and frequency is measured in Hertz (Hz). Hertz is also equal to (s/1). Some questions ask for the wavelength in nanometers so I would be careful of those and make sure to convert my answer at the end.

Helena Hu 3E
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Joined: Wed Sep 30, 2020 9:35 pm

### Re: Units for wavelength/frequency

While we're on this topic, can someone explain what an Angstrom is and how to convert to it from meters?

SophiaNguyen_2L
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Joined: Wed Sep 30, 2020 9:59 pm

### Re: Units for wavelength/frequency

Helena Hu 3E wrote:While we're on this topic, can someone explain what an Angstrom is and how to convert to it from meters?

An Angstrom simply just another unit of measurement and is 1.0 * 10^-10 meters. To convert from meters to Angstroms, you'd have to move the decimal ten places to the right. To convert from Angstrom to meters, you move the decimal ten places to the left. Hope this helps!

Kristina Krivenko 3I
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### Re: Units for wavelength/frequency

The unit for frequency is Hz (Hertz). 1 Hz = 1 $s^{-1}$, and they are use interchangeably.

The SI unit for wavelength is meters. However, since the value of wavelengths is typically very small, problems often give us the value of wavelength in nanometers. In that case, make sure to convert it to meters before plugging it in the formula.

I think it would be best to convert your final answer to the units the problem is asking for, especially since the midterm is multiple choice.

Margaret Xu 3C
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Joined: Wed Sep 30, 2020 9:36 pm

### Re: Units for wavelength/frequency

The units for frequency are usually written in Hz (1s-1), and the unit written for wavelength is meters. However, in a lot of problems I see the wavelength written in nm. A tip is to write 10-9 behind the original number to convert from nm to m for easy calculations.

Shruti Kulkarni 2I
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Joined: Thu Oct 08, 2020 12:16 am

### Re: Units for wavelength/frequency

Wavelength is measured in m, or some variety of meters, like nanometers, which will probably be given to us in the problem itself if we need to change the length to nm or do any other conversions. Frequency is measured in Hertz (Hz), which is 1/s. This too can be converted into MHz and similar values, but it will most likely be told to us in the problem if we need to change the units.

Talia Dini - 3I
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Joined: Wed Sep 30, 2020 9:32 pm

### Re: Units for wavelength/frequency

Hey Bethany! Wavelength is usually measured in meters while frequency is usually measured in s^-1 (Hz). Since the midterm is multiple choice, I think the units you will need to find for the wavelength or frequency will not be too difficult to figure out!

Melanie Lin 3E
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Joined: Wed Sep 30, 2020 9:38 pm

### Re: Units for wavelength/frequency

Hi Bethany! Wavelengths in the visible light region (which are the ones usually used in problems) are usually in nanometers but you will often have to convert it to meters if you need to use it in a formula (especially those containing Planck's constant). Frequencies will generally be in Hz (or s^(-1)). I think as long as you have the answer that can be converted to the one in his key, you should be fine.

Savannah Torella 1L
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Joined: Wed Sep 30, 2020 9:40 pm

### Re: Units for wavelength/frequency

Wavelength is usually measured in meters, while frequency is usually measured in Hz or s^-1. However, I have seen nm used a lot on Sapling problems, so I think it would be beneficial to know how to convert between the two. Nanometer is 10^-9, so to go from nanometer to meter you would move 9 spaces to the left.

Tobie Jessup 2E
Posts: 59
Joined: Wed Sep 30, 2020 10:02 pm

### Re: Units for wavelength/frequency

The units of wavelength is meters (m) and the unit for frequency is Hertz (Hz), which is s^-1. Nano meters aren't very commonly used and it is also important to keep track of these units in these calculations, like understanding that Hz is really s^-1.

Thomas Gimeno
Posts: 55
Joined: Wed Sep 30, 2020 9:49 pm

### Re: Units for wavelength/frequency

Wave length will usually be given in nm which is m*10^-9 however there was a problem that gave wavelength in um which is only m*10^-6. Frequency is in Hz which is just 1/seconds. You can think of it a per second if that helps. It makes sense because when wave length and frequency are multiplied you get a speed measured in m/s and when you multiply m and Hz its the same as m/s.