Question

The velocity of an electron in the seventh orbit of hydrogen-like atom is 3.6 × 106 m/s. Find the velocity of the electron in the 3rd orbit.

• A. 4.2 × 106 m/s
• B. 8.4 × 106 m/s
• C. 2.1 × 106 m/s
• D. 3.6 × 106 m/s

Answer 1

Answer: (B)

8.4 × 106 m/s

Answer 2

For hydrogen like atom,
$v∝\frac{1}{n}$
$(\frac{v_1}{v_2})=(\frac{n_2}{n_1})$
$⇒ \frac{3.6\times10^6}{v_2}=\frac{3}{7}$
$⇒v_2=\frac{7}{3}\times3.6\times10^6$
= 8.4 × 106 m/s

So, the correct answer is (B) : 8.4 × 106 m/s