Example from Friday's Lecture (10/12/18)

[905085650]

Hi,

On Friday we went over a problem at the end of class that asked if the wavelength of an electron traveling at 5.3 x 10^6 m/s could be calculated. When we plugged in the numbers, we were given 9.11 x 10^-31 kg. Where does this number come from?

Thank you!!

[Jonathan Cheng 3C]

9.11 * 10^-31 kg is the weight of an electron. This value is given

[becca_vandyke_4b]

You use the mass of the electron when calculating the momentum (p) in the problem. I believe the example he gave us listed the velocity of the electron but not the mass of it. So to calculate p=(m)(v) he plugged in the mass which I guess is considered a constant.

[Mhun-Jeong Isaac Lee 1B]

Yes, Lavelle said that the mass is given. So it is safe to assume that the mass will be on the constants sheet for any tests/exams.