Achieve #15

[Nova Akhavan 2F]

I've tried to do this problem with a lot of different equations: "You use an electron microscope in which the matter wave associated with the electron beam has a wavelength of 0.0245 nm. What is the kinetic energy of an electron in the beam, expressed in electron volts?"

Could someone share the equations they used and the steps they took to get to their answer?

[Ben Zhang 2H]

I used De Broglie's equation to find the momentum of the electron. Then I found the velocity of the electron since we already know the mass of the electron. Then kinetic energy is 0.5mv^2. Then convert that answer from joules to eV.

[Hannah Joo 2D]

I took similar steps as the previous reply, but I wanted to add a couple more things! If this was one of the equations you tried to use but it didn't work, check your units. With all of the equations for chemistry, units have to match up. For instance when finding the velocity using wavelength = h/(m x v), mass should be in kilograms and wavelength in meters. When you're plugging in the velocity to find the KE of the electron, mass is in kilograms and velocity is in m/s.

[Claire Kim 1F]

I've tried to do this problem with a lot of different equations: "You use an electron microscope in which the matter wave associated with the electron beam has a wavelength of 0.0245 nm. What is the kinetic energy of an electron in the beam, expressed in electron volts?"

Could someone share the equations they used and the steps they took to get to their answer?

I believe this is what you do:
wavelength : 0.0245 x 10^-9m
using the wavelength = h/(mv) --> (0.0245 x 10^9m) = (6.626 x 10^-34)/[(9.109 x 10^15)(v)]
Once you get the value of v, plug that into the KE equation which is 0.5mv^2. Then the KE will be in J so convert that into eV units.