Question

In an atom, two electrons revolve around the nucleus in circular orbits of radii r and 4r. The ratio of the time taken by them $\left(T_2:T_1\right)$ to complete one revolution is

• A. 1:4
• B. 4:1
• C. 8:1
• D. 1:8

Answer 1

Answer: (C)

$r_n=n^2\times \eta$
$r_2=4\eta$
$T_n=\frac{n^3}{Z^2}\times 1.5\times 10^{-16}sec$
$T_1=\frac{1^3}{1^2}\times 1.5\times 10^{-16}sec$
$T_2=\frac{2^3}{1^2}\times 1.5\times 10^{-16}sec$
On dividing $T_2$ by $T_1$ we get
$\frac{T_2}{T_1}=\frac{8}{1}$