A series of lines in the emission spectrum of hydrogen that involve transitions to the n=2 state from states with n>2. <ref>http://antoine.frostburg.edu/chem/senese/101/electrons/glossary.shtml</ref> | A series of lines in the emission spectrum of hydrogen that involve transitions to the n=2 state from states with n>2. <ref>http://antoine.frostburg.edu/chem/senese/101/electrons/glossary.shtml</ref> |