5 Emission lines in the spectrum of hydrogen Niels Henrik David Bohr
(1885 – 1962) Danish
physicist who explained the
spectrum of hydrogen atom
based on quantum ideas He gave a theory of nuclear
fission based on the liquid-
drop model of nucleus Bohr contributed to the
clarification of conceptual
problems 
in 
quantum
mechanics, in particular by
proposing the comple-
mentary principle