Achieve Question 15

[Kaija Frassrand 2F]

I can't figure out how to go about doing this. I'm using the De Broglie formula, then plugging v into Ke= 1/2mv^2 but it's not working. Can someone help me with the steps to how to solve this?

[Hao Tam Tran 3H]

Hi!

The first step should be using the de Broglie equation for the wavelength of 0.0369 x 10^-9 m, so if you rearrange the equation you get v = h/(m(lamdha)). Then, you can substitute this into the kinetic energy equation equation (1/2)mv^2, giving you KE = (1/2) * m * (h/(m(lamdha)))^2. Now, the values of each should be as follows:

m = mass of an electron = 9.109 x 10^-31 kg
h = planck's constant = 6.626 x 10^-34 J
lamdha = 0.0369 x 10^-9 m

Thus, when calculating this out, your answer should be 1.77 x 10^-16 J. Now, the question is telling you to convert this to electron volts, so the actual answer should be 1.10 x 10^3 eV.