What Makes Electric Motor Armatures Spin?

Electric motors are the unsung heroes of our modern world, quietly powering everything from household gadgets to industrial giants. At the heart of these marvels lies the armature—a key player responsible for turning electrical energy into the mechanical motion that drives our machines. In this article, we’ll take a closer look at how armature rotation happens in electric motors, breaking down the process into simple steps.

The Armature: The Motor’s Mover and Shaker

Think of the armature as the motor’s spinning core, made up of a coil of wire wound around a central core, usually crafted from laminated steel. When electricity flows through this wire coil, it creates a magnetic field that interacts with the stationary magnets or electromagnets nearby.

Magnetic Fields at Play

Here’s where things get interesting. Remember those magnets we mentioned? Well, they’re not just there for decoration. When the magnetic field generated by the armature meets the magnetic field of the stationary magnets or electromagnets, they start pushing and pulling against each other. This push and pull force is what makes the armature spin.

The Role of Lorentz Force

Now, let’s talk about the Lorentz force. Named after physicist Hendrik Lorentz, this force is like the invisible hand guiding the armature’s motion. It’s created when the magnetic field from the armature’s current interacts with the external magnetic field. This force pushes the armature in a direction perpendicular to both the current flow and the magnetic field lines, causing it to spin.

Keeping the Spin Going: Commutation

In direct current (DC) motors, like the ones in your car or certain appliances, there’s a clever trick called commutation that keeps the armature spinning smoothly. Essentially, it involves switching the direction of the electric current in the armature at just the right moment as it rotates. This ensures that the armature keeps turning in the same direction, powering whatever the motor is connected to.


In the intricate world of electric motors, the armature emerges as a pivotal force, seamlessly converting electrical energy into the mechanical motion that drives our machines. Through a harmonious dance of magnetic fields and the guiding hand of the Lorentz force, the armature spins with precision, propelling us into a realm of endless possibilities. By unraveling the mysteries behind armature rotation, we gain a newfound appreciation for the ingenious mechanisms shaping our modern world.

Key Takeaways

  1. The armature, composed of wire coils wound around a central core, serves as the driving force within electric motors, transforming electrical energy into mechanical motion.
  2. Magnetic fields generated by the armature interact with stationary magnets or electromagnets, resulting in a push-and-pull force that induces armature rotation.
  3. The Lorentz force, a product of the interaction between the armature’s magnetic field and external magnetic fields, guides the direction of armature rotation.
  4. Commutation, a clever technique used in DC motors, ensures smooth and continuous armature rotation by reversing the direction of electric current at strategic moments.


What happens if the armature encounters resistance during rotation?

If the armature encounters resistance, such as increased load or friction, the motor may require more electrical energy to maintain rotation. Excessive resistance can lead to overheating and potential damage to the motor.

How does armature rotation differ between DC and AC motors?

In DC motors, armature rotation is achieved through commutation, which ensures continuous rotation in one direction. In AC motors, armature rotation is driven by alternating current, resulting in a changing magnetic field that induces rotation in both directions.

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