Question

The longest wave length radiation emitted in the emission spectrum when the pion de-excites from n = 3 to ground state lies in which of the following region?

• A. UV
• B. Visible
• C. Infra-red
• D. Cannot be calculated

Answer 1

The correct option is D Cannot be calculated

3$\to$1 $\Rightarrow$ $\frac{h}{\lambda }$ = (2.18 $\times$ 10${}^{-18}$ $\times$ 273) $\times$ Z${}^2$ $\times$ ($\frac{1}{1^2}$ - $\frac{1}{3^3}$)
$\Rightarrow$ depends on Z${}^2$