Physics Dept. Demonstration Manual

DHT24 - Seebeck effect

Objective: To demonstrate the Seebeck effect


  • JOI Lighting Product that transforms candle heat into LED light
  • Lighter


(Only use a fresh, unburned 4 hour tea light candle, 5/8" high. Do not re-light a used tea light)

1. Place JOI on a level surface.

2. Open door. Light candle.

3. Important: Allow candle to burn for 45 sec. with door open or candle may snuff out.

4. Close and latch door.

5. LED's may take up to 5 minutes to start.




JOI uses thermoelectric technology to convert a temperature difference into electricity. At the center of JOI is a unique thermoelectric module. The patented JOI design activates its LED lights by creating a hot side and a cold side on the module, and when this happens a principle called the “Seebeck Effect” causes electrons to flow within the module.

The Seebeck effect is a phenomenon in which a temperature difference between two dissimilar electrical conductors or semiconductors produces a voltage difference between the two substances.

When heat is applied to one of the two conductors or semiconductors, heated electrons flow toward the cooler one. If the pair is connected through an electrical circuit, direct current (DC) flows through that circuit.

Thomas Johann Seebeck discovered the phenomenon in the 1800s. More recently, in 2008, physicists discovered what they are calling the spin Seebeck effect. The spin Seebeck effect is seen when heat is applied to a magnetized metal. As a result, electrons rearrange themselves according to their spin. Unlike ordinary electron movement, this rearrangement does not create heat as a waste product. The spin Seebeck effect could lead to the development of smaller, faster and more energy-efficient microchips as well as spintronics devices.

- Thanks to Pam Borman for suggesting this demonstration