Question

If an electron in hydrogen atom jumps from an orbit of level $n=3$ to an orbit of level $n=2$, emitted radiation has a frequency.
(R = Rydberg's constant, c = velocity of light)

• A. $\frac{3Rc}{27}$
• B. $\frac{Rc}{25}$
• C. $\frac{8Rc}{9}$
• D. $\frac{5Rc}{36}$

Answer 1

The correct option is D $\frac{5Rc}{36}$

When an electron jumps from orbit $n_i$ to orbit $n_f(n_i>n_f)$, the frequency of emitted photon is given by
$v=cR[\frac{1}{n_f^2}-\frac{1}{n_i^2}]\Rightarrow v=cR[\frac{1}{2^2}-\frac{1}{3^2}]$
$v=cR\left[\frac{5}{36}\right]\Rightarrow v=\frac{5cR}{36}$