Physics: How Coil Turns Tune an Electromagnet's Power

Electromagnets sit at the heart of countless devices, from doorbells and cranes to motors and loudspeakers, and their defining feature is that their strength can be controlled. Unlike a permanent bar magnet, whose field is fixed, an electromagnet produces magnetism only while current flows through a coil, usually wrapped around an iron core. This makes its strength adjustable, which is precisely what makes it so useful in practical applications. The key relationship is straightforward: each turn of wire carries the same current and generates its own small magnetic field. Adding more turns means these individual fields combine, so the total field strength grows and the electromagnet can attract more magnetic material, such as paper clips. Increasing the current or improving the core has a similar effect. Because its strength can be tuned, an electromagnet can be made weaker or stronger than a bar magnet simply by changing the number of coil turns, giving it far greater versatility.