Question

In a sample of hydrogen like atoms all of which are in ground state , a photon beam containing photons of various energies is passed.In absorption spectrum, five dark lies are observed. The number of bright lines in the emission spectrum will be (Assume that all transitions take place)

• A. 5
• B. 10
• C. 15
• D. none of these

Answer 1

The correct option is C 15

Number of lines in absorption spectrum $=(n-1)$
$\Rightarrow 5=n-1\Rightarrow 6$
$\therefore$ Number of bright lines ion the emission spectrum
$=\frac{n(n-1)}{2}=\frac{6(6-1)}{2}=15$