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  • A beam of monochromatic light is used to excite the electron in f

A beam of monochromatic light is used to excite the electron in \mathrm{Li^{++}} from the first orbit to the third orbit. The wavelength of monochromatic light is found to be \mathrm{x\times 10^{-10}m}. The value of \mathrm{x} is __________.

( Given \mathrm{hc=1242 eVnm} )

Option: 1

114


Option: 2

-


Option: 3

-


Option: 4

-


Answers (1)

best_answer

\mathrm{E=-13.6 \frac{z^{2}}{n^{2}} \mathrm{eV}}

When electron jumps, excited state energy difference will be provided by light \mathrm{\left ( z=3 \right )}

\mathrm{E_{f}-E_{i}=\frac{h c}{\lambda}} \\

\mathrm{\left(-13.6 \times \frac{9}{9}\right)-\left(-13.6 \times \frac{9}{1^{2}}\right)=\frac{h c}{\lambda}} \\

\mathrm{9 \times 13.6-13.6=\frac{h c}{\lambda}} \\

\mathrm{8 \times 13.6\: eV=\frac{1242}{\lambda} \mathrm{eV} \mathrm{nm}} \\

\mathrm{\lambda=114 \times 10^{-10} \mathrm{~m}}

Hence the answer is \mathrm{114 \times 10^{-10} \mathrm{~m}}

Posted by

Shailly goel

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