Physics – 4.5.3 Magnetic effect of a current | e-Consult

The strength of the magnetic field produced by a coil carrying a current is directly proportional to both the current (I) and the number of turns (N) in the coil. This relationship is described by the formula: B = μ₀NI, where:

• B is the magnetic flux density (strength of the magnetic field) in Tesla (T).
• μ₀ is the permeability of free space (a constant value).
• N is the number of turns in the coil.
• I is the current flowing through the coil in Amperes (A).

Effect of changing the current (I): Increasing the current increases the number of moving charges within the wire, resulting in a stronger magnetic field. More moving charges mean a stronger magnetic field.

Effect of changing the number of turns (N): Increasing the number of turns in the coil concentrates the magnetic field. Each turn contributes to the overall magnetic field strength. More turns mean a stronger magnetic field.

Effect of an Iron Core: Inserting an iron core into the coil significantly enhances the magnetic field. Iron is a ferromagnetic material, meaning it can be easily magnetized. The iron core concentrates the magnetic flux lines, effectively multiplying the magnetic field strength. The iron core provides a low reluctance path for the magnetic flux, reducing the flux leakage into the surrounding air.