Calculate Min Potential to View K Alpha Line for an Element

[Eratosthenes]

I am trying to calculate the minimum potential required to view a K alpha line for a certain element:

After some algebra I have

E = hc*R_inf*(Z - 1)^2 * (1 - 1/n^2)

Why must n->inf in order for me to view the K alpha line for the element?

I did the problem and I just used n = 2, because my book says the lowest frequency line corresponds to the lowest energy transition, n = 2 to n = 1. Then it goes on to say that this line is the K alpha line, so I don't get why they would use infinity. I must be missing something vital.

If anyone can help it would be great.

 

[Valerie Park]

The reason why n must approach infinity in this equation is because the K alpha line is the transition from the highest energy level (n = ∞) to the lowest energy level (n = 1). In order for the equation to correctly calculate the minimum potential required to view the K alpha line, the value of n must be set to infinity.

 

[sir-pinski]

The reason why n must approach infinity in order to view the K alpha line for an element is because the K alpha line corresponds to the transition from the K shell (n=1) to the L shell (n=2). This means that the electron in the K shell must have enough energy to jump up to the L shell. As n increases, the energy required for this transition decreases. Therefore, in order to view the K alpha line, the electron must have the minimum energy possible, which occurs when n approaches infinity. This is because at infinity, the energy required for the transition is at its lowest possible value, and any further increase in n would result in a higher energy transition. So, while n=2 may correspond to the lowest frequency line, it may not necessarily correspond to the K alpha line. I hope this helps clarify why n must approach infinity for the K alpha line to be viewed.