Atoms

Hydrogen atom is bombarded with electrons accelerated through a potential difference of V, which causes excitation of hydrogen atoms. If the experiment is being performed at T=0 K, the minimum potential difference needed to observe any Balmer series lines in the emission spectra will be 10 V, where = .

Answer

121

Solution

At T = 0 K all atoms are in the ground state (n = 1).

∵ Balmer lines end on n = 2, the atom must be raised at least to n = 3 (line 3 → 2)

eV=E3-E1=13.6 (1- 19 ) eV

=12.09 eV 12.1 eV

V=12.1 V= 12110 V

=121

Answer: 121