suggested grade levels: 4- 8

Overview:
In this experiment, you will create invisible shock waves that are strong enough to blow out a candle. Earthquakes release tremendous amounts of energy that can cause seismic waves. These are also called shock waves but earthquake shock waves travel through the earth. In this activity you will have the opportunity to observe the impact that shock waves can have on a small scale. This activity will help students understand about the impact that seismic waves can have.

Procedure:
Use the Earthquake section of the Digital Atlas of Idaho. To get there: Click on Atlas Home, mouse-over Geology, then click on Earthquakes. Click on the beginning concepts module for a review on seismic waves.

1. Remove the metal spout from the empty salt container.
2. Ask an adult to light the candle for you.
3. Stand about 3 feet (1 m) away from the candle, and aim the hole in the container at the candle.
4. Sharply thump the end of the container facing you with your finger.
5. Move a little closer to the candle and thump the container again. Then move a little farther away from where you started. How far away can you move and still send out a wave that blows out the candle?
Remember: Your aim must be true for this shock wave to work.

What Happens and Why:
The thumping action creates a shock wave in the air, which flows in the direction of the candle, making the flame move. Shock waves that flow through Earth are also invisible but have an effect on the things they contact. In this experiment, the shock wave can also be called a sound wave. When the shock wave hit your eardrums, it moved them just as it moved the candle flame, causing you to hear the thumping sound.

Handouts/Activity links:
These are links to access the handouts and printable materials.
Earthquakes

Related Lesson Topics:
Geology: Geology Topics