Under the correct conditions, the element molybdenum emits X-rays with a characteristic wavelength of 0.711A (7.11*10^-11m). These X-rays are used in diffraction experiments to determine molecular structures. How fast does an electron need to be moving to have the same wavelength as these X-rays?
Wavelength=h/mv
7.11*10^-11m= (6.626*10^-34J*s) / mv
I'm stuck. How do I know what "m" is? Is it just the atomic mass of Molybdenum, 95.9amu?
3 answers
No. Aren't you interested in the speed of the electron. So it's the mass of the electron (in kg I think).
Oh, yes that's right. Mass of electron= 9.11*10^-31kg.
Therefore v=1.02*10^7m/s
Therefore v=1.02*10^7m/s
That looks ok to me. I didn't check the arithmetic.
1 answer