In an atom an electron excites to the fourth orbit.When it jumps back to the energy level one a spectrum is formed. Total number of spectral lines in this spectrum would be
The relation to find number of spectral lines is (n2−n1)(n2−n1+1)2
Here transition is from n = 4 to n = 1
So, number of spectral lines = 3×42=6
Hence, there are 6 spectral lines.