question_answer

In the given figure the steady state current in \[2\,\,\Omega \] resistor is :

A)  zero           

B)  0.6 A

C)  0.9 A          

D)  1.5A

Correct Answer: C

Solution :

From Bohrs atomic relation \[{{r}_{n}}=\frac{{{\varepsilon }_{0}}\,{{n}^{2}}{{h}^{2}}}{\pi \,m\,Z{{e}^{2}}}\] or \[{{r}_{n}}\propto {{n}^{2}}\] where h is Plancks constant, Z is atomic number and m is mass. Given, \[{{r}_{1}}=0.53\,\,\overset{o}{\mathop{A}}\,,\,\,{{n}_{1}}=1,\,{{n}_{2}}=4\] \[\therefore \] \[\frac{{{r}_{1}}}{{{r}_{2}}}=\frac{{{n}^{2}}}{{{n}_{2}}^{2}}\] \[\frac{0.53}{{{r}_{2}}}=\frac{1}{16}\] \[\Rightarrow \] \[{{r}_{2}}=0.53\times 16=8.48\,\overset{o}{\mathop{A}}\,\]