This experiment shows how magnets and electricity work together to create sound. It’s a great hands-on activity for science teachers, homeschoolers, and curious kids with close adult supervision.

In this guide, you will learn what sound is, why magnets are inside every speaker, and how to turn a paper plate, cup, or box into a working speaker using a magnet and a coil of wire.

What is sound?

First, it helps to understand what sound is. Sound is vibration. When something vibrates, it pushes and pulls the air around it. Those tiny pushes and pulls travel through the air as sound waves. When the waves reach your ear, your brain interprets them as sound.

A speaker’s job is simple. It vibrates on purpose, very quickly, in patterns that match music or voices. The better the vibration control, the clearer the sound.

If you want to demonstrate sound in class, here's a quick example. Tap a desk, stretch a rubber band and pluck it, or hold a phone close to a table while music plays. You can often feel the vibration even before you focus on the sound.

Why are magnets found in all speakers?

Every common loudspeaker includes two key parts:

  • A permanent magnet, which creates a steady magnetic field
  • A coil of wire, often called a voice coil, which becomes an electromagnet when an electrical current flows through it

When music plays, the electrical signal travels through the coil. That changing signal makes the coil’s magnetic field change direction and strength. The coil sits inside the permanent magnet’s field, so the two magnetic fields push and pull on each other. That motion makes the cone or the surface attached to the coil vibrate, creating sound waves.

In plain language, magnets help convert an electrical signal into movement. Movement becomes vibration. Vibration becomes sound.

 

Why are magnets necessary in speakers?

A coil of wire by itself does not move much. The permanent magnet provides a strong magnetic field so the coil has something to push against. This is why magnets are essential. They create the force that moves the speaker's surface back and forth.

Neodymium magnets are common in modern speakers because they provide strong magnetic fields in a small size.

The experiment: turn household objects into speakers

This project creates a simple working speaker using:

  • A lightweight surface to vibrate
  • A coil of wire
  • A small, strong magnet
  • An audio source

You can use a paper plate, plastic cup, shallow cardboard box, or even a food container lid. Each one produces a slightly different sound because the material vibrates differently.

 

What you will need

Materials

  • 1 neodymium magnet (a small block or disc works well)
  • Enameled copper wire (often labeled magnet wire)
  • Tape
  • Paper plate, plastic cup, or thin cardboard
  • An old headphone cable or 3.5 mm audio cable to connect to a phone or tablet
  • Sandpaper or a metal scraper for removing enamel from wire ends
  • Optional: a small piece of cardboard for mounting

Apex tip for teachers: A small neodymium block magnet is easy to handle, stable on a table, and strong enough to make the effect obvious. Remember that neodymium magnets are very powerful; always supervise students and remind them that these strong magnets can snap and pinch fingers.

Step-by-step instructions

Step 1: Make the wire coil

Wrap the magnet wire into a flat coil about the size of your magnet. Aim for 20 to 50 wraps. More wraps usually gives a stronger sound.

Leave 6 inches of wire on both ends so you can connect it to your audio cable.

Step 2: Remove the enamel from the wire ends

Magnet wire is coated with a thin enamel layer that prevents electricity from flowing between turns. You must remove it from the two wire ends so electricity can flow into the coil.

Use sandpaper or gently scrape the last 1 inch of each wire end until the copper looks shiny.

Step 3: Attach the coil to your speaker surface

Tape the coil to the center underside of your paper plate or the bottom of an upside-down plastic cup. Keep it flat so it can move freely.

Try not to crush the coil. You want it snug but not too tightly pinned down.

Step 4: Place the magnet under the coil

Place the neodymium magnet on a table. Position the paper plate or cup so the coil sits directly above the magnet with a small gap. The coil should not rub against the magnet too hard.

You will need to ensure there is a small gap. If the coil is too far away, the magnetic force is weak, and the sound is faint. If it touches too much, it can scrape and distort the sound.

Step 5: Connect to audio

Cut an old headphone cable and strip the two speaker wires, or use a 3.5 mm audio cable with exposed ends.

Twist or tape each stripped cable wire to one end of the coil. Make the connections firm.

Step 6: Play the sound quietly first

Start with low volume. Play music, a tone generator, or spoken audio. Then slowly increase the volume until you hear vibration and sound.

If you hear nothing, check these common issues:

  • The wire ends still have enamel on them
  • The coil is not centered over the magnet
  • The connections to the audio cable are loose
  • The coil is too far away from the magnet

Science teachers can turn this into a quick troubleshooting lesson on circuits and cause-and-effect.

Make it more fun: test different objects

Once you get sound, try swapping the vibrating surface:

  • A paper plate for a louder sound
  • Plastic cup for a more focused sound
  • Thin cardboard for a deeper tone
  • Container lid for a rattly effect

Ask students to predict which material will sound best and why, then test it. This helps students connect sound to vibration and material properties.

What this experiment demonstrates

This experiment shows three core ideas in a way you can see and hear:

  1. Sound is a vibration that travels through the air
  2. Electricity can create magnetism in a coil of wire
  3. A magnetic field can turn electrical signals into motion, which becomes sound

This is the same basic principle used in real speakers, just simplified.

Safety notes for home and classroom use

Neodymium magnets are strong. Keep magnets out of reach of small children, and do not allow students to handle multiple magnets unsupervised.

Keep magnets away from sensitive electronics and magnetic stripe cards. Also, use caution around medical devices such as pacemakers. Avoid letting magnets snap together because they can pinch fingers or chip.

Build your next classroom demo with Apex Magnets

At Apex Magnets, we help educators and DIYers find the right magnet for hands-on experiments. Our team offers practical guidance, fast shipping from a fully stocked U.S. warehouse, and over 20 years of magnet experience.

If you want help selecting a magnet size for this experiment or planning a classroom set, reach out to our team, and we will point you in the right direction.

 

Safety Warning: Children should not be allowed to play with neodymium magnets as they can be dangerous. Small magnets pose a choking hazard and should never be swallowed or inserted into any part of the body.

Magnets can be dangerous. Neodymium magnets, especially, must be handled with care to avoid personal injury and damage to the magnets. Fingers and other body parts can get severely pinched between two attracting magnets. Bones can be broken by larger magnets. Visit our Magnet Safety page to learn more.