An electron travelling horizontally towards west enters into a magnetic field acting vertically down wards. It deflects towards

Options

A. South
B. North
C. Vertically upwards
D. North - East

Answer

To solve the problem of determining the direction in which an electron deflects when it enters a magnetic field, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Direction of the Electron's Velocity (V)**:
- The electron is traveling horizontally towards the West.

2. **Identify the Direction of the Magnetic Field (B)**:
- The magnetic field is acting vertically downwards.

3. **Use the Right-Hand Rule to Determine the Direction of the Magnetic Force (F)**:
- For a positive charge, the force due to the magnetic field can be determined using the right-hand rule. However, since we are dealing with an electron (which has a negative charge), we will need to consider the opposite direction.
- According to the right-hand rule:
- Point your fingers in the direction of the velocity (West).
- Curl your fingers in the direction of the magnetic field (downwards).
- Your thumb will then point in the direction of the force for a positive charge.

4. **Determine the Resulting Force Direction**:
- If we apply the right-hand rule:
- Fingers point West (the direction of the electron's velocity).
- Curl downwards (the direction of the magnetic field).
- The thumb points towards the South (this is the direction of the force for a positive charge).
- Since the electron is negatively charged, the force acting on it will be in the opposite direction to that indicated by the thumb, which means the force will be directed towards the North.

5. **Conclusion**:
- Therefore, the electron deflects towards the North.

### Final Answer:
The electron deflects towards the North.

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