Finding the wavelength of an ejected atom

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Siwa Hwang 3G
Posts: 34
Joined: Wed Sep 30, 2020 9:48 pm

Finding the wavelength of an ejected atom

Postby Siwa Hwang 3G » Mon Oct 26, 2020 8:01 pm

If the wavelength of incident light on sodium metal was 810 nm, and the work function of
sodium is 1.1 eV, what is the wavelength of the ejected electron?

I found the KE of an ejected atom using E - work function = KE but I don’t know how to find the wavelength. Is there a specific formula that I should be using?

Please help out If you can!

Cecilia Cisneros 1J
Posts: 79
Joined: Wed Sep 30, 2020 9:45 pm

Re: Finding the wavelength of an ejected atom

Postby Cecilia Cisneros 1J » Mon Oct 26, 2020 8:03 pm

If you found the KE then you can use the equation:
KE = 1/2mv^2 to solve for the velocity of the electron.
Then you can use the de broglie equation:
wavelength = h/mv to solve for the wavelength of the electron.

Samuel Flores 2C
Posts: 35
Joined: Wed Sep 30, 2020 9:51 pm

Re: Finding the wavelength of an ejected atom

Postby Samuel Flores 2C » Mon Oct 26, 2020 8:13 pm

Hello! The best way to solve these type of problem is to find the velocity of the electron, with the equation KE=(1/2)mv^2. If you know the KE of the electron, plug this into the equation to solve for the velocity of the electron.

Once we know the velocity of the ejected electron, then we can apply De Broglie's equation: λ=h/mv. By plugging in the velocity, we can solve for the wavelength of the electron.

Hope this helps!

Lily Kiamanesh 3D
Posts: 42
Joined: Wed Sep 30, 2020 10:09 pm

Re: Finding the wavelength of an ejected atom

Postby Lily Kiamanesh 3D » Mon Oct 26, 2020 8:43 pm

Hi! I did this problem using de Broglie's equation, and I got 1.87 * 10-9 m. I was wondering if anyone got the same thing?

Siwa Hwang 3G
Posts: 34
Joined: Wed Sep 30, 2020 9:48 pm

Re: Finding the wavelength of an ejected atom

Postby Siwa Hwang 3G » Wed Oct 28, 2020 12:59 am

Okay I followed your guys’ instruction and I got 1.87 x 10 ^-9 m.


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