<Tr> <Td> 6 </Td> <Td> 93.780 </Td> </Tr> <Tr> <Td> ∞ </Td> <Td> 91.175 </Td> </Tr> <P> Named after Johann Balmer, who discovered the Balmer formula, an empirical equation to predict the Balmer series, in 1885 . Balmer lines are historically referred to as "H - alpha", "H - beta", "H - gamma" and so on, where H is the element hydrogen . Four of the Balmer lines are in the technically "visible" part of the spectrum, with wavelengths longer than 400 nm and shorter than 700 nm . Parts of the Balmer series can be seen in the solar spectrum . H - alpha is an important line used in astronomy to detect the presence of hydrogen . </P> <Table> <Tr> <Th> n </Th> <Th> λ, air <P> (nm) </P> </Th> </Tr> <Tr> <Td> </Td> <Td> 656.3 </Td> </Tr> <Tr> <Td> </Td> <Td> 486.1 </Td> </Tr> <Tr> <Td> 5 </Td> <Td> 434.0 </Td> </Tr> <Tr> <Td> 6 </Td> <Td> 410.2 </Td> </Tr> <Tr> <Td> 7 </Td> <Td> 397.0 </Td> </Tr> <Tr> <Td> ∞ </Td> <Td> 364.6 </Td> </Tr> </Table>

Explain why the emission spectrum of hydrogen atom is line spectrum