In the generation of X-rays with an X-ray tube, the minimum wavelength λmin that is produced is given by λmin=hc/eV where h=Planck's constant,6.6261×10−34J⋅s, c=speed of light,2.9979×108m/s, e=elementary charge,1.6022×10−19C, and V=the tube voltage. Therefore, λmin=1240/Vnm The wavelength of maximum X-ray emission λpeak is approximately 3/2 times the minimum wavelength. That is, λpeak≈1860/Vnm Table 3.1 lists λmin and λpeak as functions of V.