The coefficient of mutual induction between two closely lying coil does not depend upon__

Options

A. their mutual orientation
B. the permeability of their core material
C. their structure
D. the current flowing in them

Answer

To determine what the coefficient of mutual induction between two closely lying coils does not depend on, we can analyze the factors that influence mutual inductance.

### Step-by-Step Solution:

1. **Understanding Mutual Inductance (M)**:
- The coefficient of mutual inductance (M) between two coils is a measure of how much the magnetic field created by one coil induces an electromotive force (EMF) in the other coil.

2. **Factors Influencing Mutual Inductance**:
- Mutual inductance depends on several factors:
- **Number of Turns (N1 and N2)**: More turns in either coil will increase the mutual inductance.
- **Area of the Coils**: The larger the area of the coils, the greater the magnetic flux linkage, hence increasing mutual inductance.
- **Distance Between Coils**: The closer the coils are to each other, the stronger the mutual inductance.
- **Orientation of Coils**: The angle between the coils affects the amount of magnetic flux that links them.

3. **Factors Not Influencing Mutual Inductance**:
- The coefficient of mutual induction does not depend on:
- **Current Flowing Through the Coils**: While the current is involved in the calculation of the magnetic field, the mutual inductance itself is a property of the coils and does not change with the amount of current flowing through them.

4. **Conclusion**:
- Therefore, the coefficient of mutual induction between two closely lying coils does not depend on the current flowing through them.

### Final Answer:
The coefficient of mutual induction between two closely lying coils does not depend on the current flowing through them.

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