In: Physics
A. What is the minimum wavelength of x-rays?
Knowns: 45 KeV at a tungsten target
B. an electron in hydrogen goes from n = 5 to the n = 3 energy level.
What wavelength of light is emitted?
A.
Energy of electrons,E=45keV=451.6
10-19
J
Also
E=hc/
So,minimum wavelength of X-ray is
=hc/E=(6.63
10-34
3
108)/(45
1.6
10-19
)=2.76
10-8
m
B.
Energy of transition from one state to other in H-atom is
E=-13.6eV[1/(n1)2-1/(n2)2]
Also
E=hc/
n1=5 and n2=3
so
E=-13.6eV[1/(5)2-1/(3)2]=-13.61.6
10-19[1/(5)2-1/(3)2]=1.55
10-19
J
So
Wavelength of emitted light is
=hc/E=(6.63
10-34
3
108)/(1.55
10-19
)=1.29
10-6
m