Question

The velocity of electron in the second Bohr orbit of H atom is:

• A. $2.19\times {10}^{8}cm{s}^{-1}$
• B. $4.38\times {10}^{8}cm{s}^{-1}$
• C. $7.2\times {10}^{8}cm{s}^{-1}$
• D. $1.09\times {10}^{8}cm{s}^{-1}$

Answer 1

The correct option is D $1.09\times {10}^{8}cm{s}^{-1}$

$v=\frac{2\pi e^2}{h}$

For $I^{st}$ Bohr orbit,

$v=\frac{2\times 3.14\times (4.8\times {10}^{-10}{)}^2}{6.63\times {10}^{-27}}=2.19\times {10}^{8}cm{s}^{-1}$

For II orbit, $v_n=\frac{v_1}{n}$,

$v_2=\frac{2.19\times {10}^8}{2}=1.09\times {10}^{8}cm{s}^{-1}$.