- #1

cooper607

- 49

- 0

## Homework Statement

a beam of electrons bombards a sample of hydrogen. through what potential difference must the electrons have been accelerated if the first line of balmer series is to be emitted

## Homework Equations

1/l=R(1/2^2-1/3^2)

E=hc/l

v=E/Q

## The Attempt at a Solution

i first tried to find the wavelngth corresponding to first balmer series where i put ni=2 &nf=3.. first let me know if this interpretation is correct

then i found the wavelength l=6.563* E-7 m

according to E=3.03*E-19J

and finally V=E/Q=1.89 V

but the result has to be 12.1 V

please let me know where's the problem

regrds