You’ve turned your pickle into a battery! Here’s how it works:
Pickles contain salt water, which is rich in charged particles called ions. The aluminum and the graphite react with these ions, setting off an electrical tug-of-war between the two materials. The material with the stronger pull—aluminum—takes electrons away from the graphite, triggering a flow of electrons around the circuit. This current powers the buzzer.
Most common batteries—such as your car battery and the batteries inside your flashlight—work on the same principle that your pickle battery works on: They use two metals suspended in an ion-rich liquid or paste to separate electric charge, and create an electrical current around a circuit.
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Make a robot friend with Adafruit’s CRICKIT – A Creative Robotics & Interactive Construction Kit. It’s an add-on to our popular Circuit Playground Express, FEATHER and other platforms to make and program robots with CircuitPython, MakeCode, and Arduino. Start controlling motors, servos, solenoids. You also get signal pins, capacitive touch sensors, a NeoPixel driver and amplified speaker output. It complements & extends your boards so you can still use all the goodies on the microcontroller, now you have a robotics playground as well.