The X-ray spectrum of an X-ray tube with a molybdenum target is shown. The K edge (K-electron binding energy) is 0.0617 nm. The lowest voltage that could produce the spectrum shown is
A) 10 kV
B) 20 kV
C) 30 kV
D) 40 kV
E) 50 kV

Question

The X-ray spectrum of an X-ray tube with a molybdenum target is shown. The K edge (K-electron binding energy) is 0.0617 nm. The lowest voltage that could produce the spectrum shown is
A) 10 kV 
B) 20 kV 
C) 30 kV 
D) 40 kV 
E) 50 kV

Quizplus · Accepted Answer

The lowest voltage that could produce the spectrum is determined by the energy required to exceed the K-edge, which is given by the equation E = hc/λ, where h is Planck's constant, c is the speed of light, and λ is the wavelength. Thus, the energy required to exceed the K-edge is E = hc/0.0617 nm = 0.00201 keV. The lowest voltage required to produce this energy is given by the equation V = E/q, where q is the charge of an electron. Thus, V = (0.00201 keV)/(1.6 × 10^-19 C) = 12.6 kV. However, this only represents the energy required to produce the Kα line, and the actual spectrum shown includes higher energy lines corresponding to Kβ emission and bremsstrahlung radiation. Therefore, a higher voltage is necessary to produce the entire spectrum, and the closest option is 30 kV (choice C).

The X-Ray Spectrum of an X-Ray Tube with a Molybdenum