The frequencies of K_ X-rays for various materials are measured. Which of the graphs in the figure could represent the relationship between the frequency and the atomic number Z ?

Step-by-step solution

According to Moseley's law, the frequency of the K_ X-ray is related to the atomic number Z of the material by the equation: = a(Z - b) where a and b are positive constants. Squaring both sides, we get: = a^2(Z - b)^2 This equation represents a parabola opening upwards with its vertex on the positive Z -axis at Z = b . From the given figure, curve d is a parabola opening upwards, which matches this relationship. Curves a and c are concave downwards, and curve b is a straight line. Thus, curve d represents the corre