Question

An electron has an angular momentum of \[ 90h\ \text{J s} \] while orbiting with a linear velocity of \[ \pi\times10^5\ \text{m s}^{-1}. \] Then the radius of the orbit is \[ \left( m_e=9\times10^{-31}\,\text{kg}, \quad h=6.6\times10^{-34}\,\text{J s} \right) \]

• A. \[ 66\times10^{-15}\ \text{m} \]
• B. \[ 33\times10^{-15}\ \text{m} \]
• C. \[ 66\times10^{-10}\ \text{m} \]
• D. \[ 33\times10^{-8}\ \text{m} \]

Hint:

For circular motion, \[ L=mvr. \] Hence, \[ r=\frac{L}{mv}. \] Always substitute the angular momentum in SI units and use \[ h=6.6\times10^{-34}\ \text{J s}. \]

Answer 1

The Correct Option is D