The origin of sound

Learn the principles of sound generation!

15 minutes


  • Carefully review the general safety advice on the back of the box cover before starting the experiment.
  • Read the “Working with Batteries” section of the safety guidelines carefully before proceeding.
  • Do not let children under 8 years old handle small magnets.
  • Disassemble the setup after the experiment.

Step-by-step instructions

Phones without a headphone jack will require an additional adapter (not included in the set).

To make the coil work more effectively, connect it to your phone via a special electrical plate called a signal amplifier.


The magnets will serve as a suspension for the pendulum.


Let's assemble the pendulum holder.


Download the MEL Physics app using the QR code. Scan the MEL code with the app. Batteries will provide the amplifier with the energy needed to boost the signal from the phone.


Here, your phone is a source of electric current. The battery-powered amplifier increases the phone current and transfers it to the coil.


Test the sonic capabilities of the box.


Play some music from the app. What changed when you attached the magnet to the box lid?



  • Dispose of solid waste together with household garbage.
  • Dispose of used batteries in accordance with local regulations.

Scientific description

Curiously, you made the magnet  move using just music from your phone and a wire! When electric current flows through the coil  , it can attract or repel the magnet . Moreover, whether the magnet  is attracted  to or repelled  from it depends on which direction the current is running.

Your phone creates the current in the wire—the same current that usually powers your headphones. Music is stored on a phone or computer in the form of a diagram  that depicts in which direction  current will run at which moment in time.

Your phone supplies the coil  with electric current, which changes directions according to the diagram , alternately attracting  or repelling  the magnet. The latter moves in a repetitive pattern along the same trajectory, swinging both ways from its position of rest. Such movement is said to be oscillatory.

Finally, the moving magnet pushes the air and creates a periodic oscillation of pressure that moves through the air. This is called a sound wave. If you set the magnet on the box lid, the sound will become louder, as the area that is vibrating along with the magnet is now much larger compared to the small plastic plate used in the first part of the experiment.