I encountered a chemical (COOEt)2C, and I don't really know what does Et mean. I am not familiar with chemistry, but I guess this is something similar to -R which stands for -CH3, -CH2CH3 etc. Could anyone help to explain?
Thanks you very much.
Homework Statement
During my calculation of hydrogen atom perturbation, I need to integral below in cartesian coordinate. It is given that below integral can be transformed.
Homework Equations
Anyone could help to see what will the transformed integral in polar coordinate if the...
"Group velocity (equal to an electron's speed) should not be confused with phase velocity (equal to the product of the electron's frequency multiplied by its wavelength)."
Above statement is from wikipedia, and I still don't quite understand it.
As one of the postulate of QM, group velocity...