An electron enters into a region of uniform magnetic field of strength 10 webers/ `m^(2)` with a speed of `3 xx 10^(7)` m/s which of the following is not possible

Options

A. The electron may or may not experience an acceleration
B. The electron may experience an acceleration but can continue to move with same speed
C. The electron may experience an acceleration and continue to move with same velocity
D. The kinetic energy of the electron remains unchanged

Explanation

To solve the problem, we need to analyze the behavior of an electron moving in a uniform magnetic field and determine which of the given options is not possible.

### Step-by-Step Solution:

1. **Understanding the Scenario**:
- An electron enters a uniform magnetic field of strength \( B = 10 \, \text{Wb/m}^2 \) with a speed of \( v = 3 \times 10^7 \, \text{m/s} \).
- The electron is a negatively charged particle.

2. **Lorentz Force**:
- The force acting on a charged particle moving in a magnetic field is given by the Lorentz force equation:
\[ F = q \cdot (v \times B) = q \cdot v \cdot B \cdot \sin(\theta) \]
- Here, \( q \) is the charge of the electron, \( v \) is its velocity, \( B \) is the magnetic field strength, and \( \theta \) is the angle between the velocity vector and the magnetic field vector.

3. **Case Analysis**:
- **Case 1**: If the electron moves parallel to the magnetic field (\( \theta = 0^\circ \)):
- The force \( F = 0 \) (since \( \sin(0) = 0 \)).
- Therefore, the electron does not experience any acceleration.
- **Case 2**: If the electron moves perpendicular to the magnetic field (\( \theta = 90^\circ \)):
- The force \( F = q \cdot v \cdot B \) (since \( \sin(90) = 1 \)).
- The electron experiences a centripetal force, causing it to move in a circular path, thus experiencing acceleration.

4. **Evaluating the Options**:
- **Option 1**: "The electron may or may not experience an acceleration."
- This is **possible** because it can either be parallel (no acceleration) or perpendicular (acceleration).
- **Option 2**: "The electron may experience an acceleration but can continue to move with the same speed."
- This is **possible** because in uniform circular motion, the speed remains constant while the direction changes.
- **Option 3**: "The electron may experience an acceleration but can continue to move with the same velocity."
- This is **not possible** because if the electron is accelerating (changing direction), its velocity (which is a vector quantity) must also change.
- **Option 4**: "The kinetic energy of the electron remains unchanged."
- This is **possible** because the speed remains constant during uniform circular motion, and thus kinetic energy does not change.

5. **Conclusion**:
- The option that is **not possible** is **Option 3**: "The electron may experience an acceleration but can continue to move with the same velocity."