What kind of magnetic field is represented by a steady current flowing through a coil?

• A. Zero magnetic field
• B. Fluctuating magnetic field
• C. Steady decreasing magnetic field
• D. Steady non-zero magnetic field

Answer: (D)

A coil carrying a steady current generates a steady non-zero magnetic field around it due to the principles of electromagnetism. According to Ampère's Law, when an electric current flows through a conductor, it produces a magnetic field in the surrounding space. In the case of a coil, the flow of electric current in the loops of wire creates a strong and uniform magnetic field, which is generally directed along the axis of the coil.

The key point here is that the current is steady, meaning it does not change over time, which results in a constant magnetic field. This differs from a fluctuating magnetic field, which would occur in situations with alternating current (AC) or where the current changes over time. The steady non-zero magnetic field can be visualized as the field lines that emerge from the ends of the coil, forming a pattern similar to that of a bar magnet.

This understanding of magnetic fields is fundamental in applications such as electromagnet design, electric motors, and transformers, where the characteristics of the magnetic field play a crucial role in the operation of these devices.