Ham Radio General Class Practice Test

How should the winding axes of solenoid inductors be placed to minimize their mutual inductance?

1. In line

2. Parallel to each other

3. At right angles

4. Interleaved

The correct answer is: At right angles

To minimize the mutual inductance between solenoid inductors, the most effective configuration is to position the winding axes at right angles to each other. When solenoids are arranged in this way, the magnetic fields generated by each inductor do not effectively link with one another. The right-angle orientation disrupts the path of the magnetic field lines that would couple between the two inductors, reducing the degree of interaction. Mutual inductance occurs when the magnetic field created by one inductor induces a voltage in another nearby inductor. By aligning the winding axes at right angles, the influence of one inductor's magnetic field on the other is diminished, thereby minimizing any induced voltage. In contrast, other configurations, such as having the axes in line or parallel, would enhance the mutual inductance because the field lines would be more effectively coupled. Interleaving, which involves mixing the windings of both inductors, would also increase mutual inductance as it maximizes the interaction of the magnetic fields. Thus, the right-angle configuration is the most effective in reducing mutual inductance between solenoid inductors.