JEE Main & Advanced Physics Atomic Physics Question Bank Self Evaluation Test - Atoms

  • question_answer
    An electron in a hydrogen atom makes a transition from \[n={{n}_{1}}\] to\[n={{n}_{2}}\]. The time period of electron in the initial state is eight times that in the final state. Then which of the following statement is true?  

    A)         \[{{n}_{1}}=3{{n}_{2}}\]

    B)  \[{{n}_{1}}=4{{n}_{2}}\]

    C)  \[{{n}_{1}}=2{{n}_{2}}\]

    D)  \[{{n}_{1}}=5{{n}_{2}}\]

    Correct Answer: C

    Solution :

    [c] In the nth orbit, let \[{{r}_{n}}\] be the radius and \[{{v}_{n}}\] be the speed of electron. Time period, \[{{T}_{n}}=\frac{2\pi {{r}_{n}}}{{{v}_{n}}}\propto \frac{{{r}_{n}}}{{{v}_{n}}}\] Now \[{{r}_{n}}\propto {{n}^{2}};{{v}_{n}}\propto \frac{1}{n}\therefore \frac{{{r}_{n}}}{{{v}_{n}}}\propto {{n}^{3}}or{{T}_{n}}\propto {{n}^{3}}\] Here \[8={{\left( \frac{n{{ & }_{1}}}{{{n}_{2}}} \right)}^{3}}\text{or}\frac{{{n}_{1}}}{n{{ & }_{2}}}=2\text{ i}\text{.e}\text{.,}{{n}_{1}}=2{{n}_{2}}\]


You need to login to perform this action.
You will be redirected in 3 sec spinner