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

Options

A. 5
B. 10
C. 15
D. 20

Answer

B

Explanation

The number of lines produced in the absorption spectrum = n-1
`therefore n-1 = 4 therefore n=5`
When the electrons from the higher orbits jump to the ground state, the possible number of lines observed in the emission spectrum `= (n(n-1))/(2) = (5xx4)/(2) = 10`