If the magnetic field is parallel to a surface then, the magnetic flux through the surface is

Options

A. (a)zero
B. (b)small but not zero
C. (c)infinite
D. (d)large but not infinite

Answer

To solve the problem of determining the magnetic flux through a surface when the magnetic field is parallel to that surface, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Magnetic Flux**:
- Magnetic flux (Φ) is defined as the product of the magnetic field (B) and the area (A) through which it passes, multiplied by the cosine of the angle (θ) between the magnetic field and the normal (perpendicular) to the surface.
- The formula for magnetic flux is given by:
\[ \Phi = B \cdot A \cdot \cos(\theta) \]

2. **Identifying the Angle**:
- In this scenario, we are told that the magnetic field is parallel to the surface. This means that the angle (θ) between the magnetic field and the area vector (which is perpendicular to the surface) is 90 degrees.

3. **Calculating Cosine of the Angle**:
- We know that:
\[ \cos(90^\circ) = 0 \]

4. **Substituting Values into the Flux Formula**:
- Now, substituting the values into the magnetic flux formula:
\[ \Phi = B \cdot A \cdot \cos(90^\circ) = B \cdot A \cdot 0 \]

5. **Conclusion**:
- Therefore, the magnetic flux through the surface is:
\[ \Phi = 0 \]

### Final Answer:
The magnetic flux through the surface is **0**.