# @stem_antics on Instagram

- **Type:** Video
- **Original URL:** https://www.instagram.com/p/DXs9HwIgNpY
- **Gondola URL:** https://gondola.cc/posts/64883916-stem-antics-instagram
- **Thumbnail:** https://img.gondola.cc/tr:w-,h-,fo-auto/postThumbnails/91b26db51e.jpg
- **Posted:** 2026-04-29T04:38:26.000+00:00
- **Account Owner:** Stem Antics (@stem_antics) — https://gondola.cc/stem_antics

## Caption

A homopolar motor is the most minimal form of an electric motor: one battery, one magnet, and a conductor. No coils, no commutator, no electronics—just direct conversion of electrical energy into continuous motion.

In this demo:

* A AA battery sits on a stack of neodymium magnets
* A heart-shaped copper wire touches the battery terminal at the top and the magnet at the bottom
* The wire begins to spin immediately

What’s happening physically:

1. Current flow
  The copper wire completes a circuit between the positive terminal of the battery and the magnet at the negative end. Charge carriers (electrons) move through the wire.
2. Magnetic field
  The magnets create a static magnetic field (B-field), typically aligned along the axis of the battery.
3. Lorentz force
  As current flows through the wire inside a magnetic field, each segment of the wire experiences a force:
 F = q(v × B) → macroscopically: F = I(L × B)
 This force is perpendicular to both the direction of current and the magnetic field.
4. Continuous rotation
  Because of the curved (heart-shaped) geometry, different segments of the wire experience forces that collectively produce torque around the battery. The system doesn’t need switching (like in conventional motors) because the current direction and magnetic field remain constant, yet the geometry keeps producing a consistent rotational force.
5. Why it keeps spinning
  As long as:

* The circuit is closed
* The wire maintains contact
* The magnetic field is present
  The force persists, and so does the motion.

Design notes for reliability:

* Use enamel-coated copper wire stripped at contact points
* Keep the wire symmetric for smoother rotation
* Stronger magnets increase force (but also friction at contact points)
* Minimize wobble to reduce energy loss

This is a direct, observable example of electromagnetism in action—specifically how electric currents interact with magnetic fields to generate motion, which is the same core principle behind all electric motors, scaled up.

#STEMeducation #PhysicsDemo #ElectricMotor #Electromagnetism #DIYScience

## Stats

- **Views:** 4,908
- **Likes:** 173
- **Shares:** 0
- **Comments:** 5

## Tags

electromagnetism, stemeducation, diyscience, electricmotor, physicsdemo

---
Copyright (c) Gondola