Hooked on Science: Battery bounce

There's an easy way to test if a battery is charged.

Materials

• Charged AA alkaline battery
• Uncharged AA alkaline battery

Instructions

STEP 1: Hold the charged AA alkaline battery so the positive end is pointing downward. Drop the battery about 4 inches from above a hard surface and observe.

STEP 2: Hold the uncharged AA alkaline battery so the positive end is pointing downward. Drop the battery about 4 inches from above a hard surface and observe.

Explanation

The uncharged alkaline AA battery will bounce more when compared to the charged alkaline AA battery. The electrolyte in an alkaline battery is a gel composed of potassium hydroxide and zinc powder. As the battery becomes uncharged, the electrolyte inside the battery goes from a gel material to a solid material, causing the uncharged battery to bounce.

Jason Lindsey is a science outreach educator with Hooked on Science. Check out his website hookedonscience.org for webcasts and experiments.