Question

What is the numerical value of angular momentum for an electron in first orbit of hydrogen atom? ( \(\mathrm{h}=6.626 \times 10^{-34} \mathrm{Js}\) )

• A. \(1.05\times 10^{-34}\)
• B. \(2.10\times 10^{-34}\)
• C. \(3.16\times 10^{-34}\)
• D. \(4.22\times 10^{-34}\)

Hint:

Use Bohr's quantisation condition for angular momentum with n equal to 1.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept
Bohr's postulate gives the angular momentum of the electron as \(L=\dfrac{nh}{2\pi}\).

Step 2: Substitution
For the first orbit \(n=1\) and \(h=6.626\times10^{-34}\) Js.
\(L=\dfrac{6.626\times10^{-34}}{2\times3.14}\)

Step 3: Calculation
\(L=\dfrac{6.626\times10^{-34}}{6.28}\approx1.05\times10^{-34}\) J s.

Final Answer:
The angular momentum is about \(1.05\times10^{-34}\) J s. \[ \boxed{\text{(A) }1.05\times 10^{-34}} \]