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
$\frac{T_{2}}{T_{1}}=\frac{8}{1}$