Achieve HW #15

[KDeguzman_Dis3K]

"You use an electron microscope in which the matter wave associated with the electron beam has a wavelength of 0.0249 nm. What is the kinetic energy of an electron in the beam, expressed in electron volts?"

For this question, I used the DeBroglie equation to find velocity, (v= h/(m)(lambda). I also converted 0.0249 nanometers to 0.0249 x 10^-9 meters.
(6.626 x 10^-34)/(9.1 x 10^-31)(0.0249 x 10^-9) = 2.92 x 10^7.

Then, I used the Kinetic energy equation and got 3.89 x 10^-16. To convert to electron volts, I multiplied this by 1.602 x 10^-19 and got 6.23 x 10^-35, yet my answer is still incorrect. Did I miss a step in the process, or is there an error in my calculations?

[Divya Hebbar]

I think you have to divide by the conversion factor instead of multiply to get Joules to eV! 3.89 x 10^-16/ 3.89 x 10^-16. = 2426 eV

[Meagan Kimbrell 1I]

I think you have to divide by the conversion factor instead of multiply to get Joules to eV! 3.89 x 10^-16/ 3.89 x 10^-16. = 2426 eV

Yup! You need to divide the joules value by 1.602x10^-19 joules since 1eV = 1.602x10^-19 joules. Not the other way around!!

[Isabella Perez Dis3L]

Hello, in your calculation you needed to divide the joules value by 1.602x10^-19 joules because 1eV = 1.602x10^-19 joules. I hope this helps!