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# Electricity and Circuits

This experiment shows that in setting up a circuit, we are able to convert electrical energy into kinetic energy. A circuit is a pathway of wires that allow electricity to flow. The flow of electricity is called the current. Current only flows when a circuit is complete. Think of the flow of electricity like the flow of water through a hose. In a complete circuit, the energy flows from the negative terminal on the power source, through the connecting wires and components, such as LEDs or a motor, and back to the positive terminal. There are a few things that we need to think about when we are making a circuit:

1. The energy source
2. The device we want to work
3. The way to get the energy to the device and back to complete the circuit

In this case, we are providing power from a battery. A battery stores energy for later use. With the type of 3V battery we are using, each side has a different polarity, or positive and negative conductors that determine the direction that the current flows. One side is marked with a plus sign and is positive, called the cathode. The other side is negative and is usually unmarked, called the anode. We will direct the electrical energy to the motor through the wires. The metal wires are called conductors because they allow electricity to flow through. Once the energy reaches the motor, it becomes kinetic energy, or energy in motion.

## Brush Bots

We can build a robot using a power source (battery), diode (motor), and a simple circuit.

### Materials

• 3V DC vibrating disk motor (look for “mini-motor” or “cell phone motor”)
• 1 3V coin cell battery (CR 2032 batteries work best)
• 1 toothbrush
• Pliers/wire cutter
• Attachment material (e.g. rubber band, tape, double-stick foam tape)
• Wire Stripper (optional)
• Googly eyes (optional)

### Procedure

1. Cut off the toothbrush head.
2. Test the battery and motor (make sure the wires are exposed and touch one wire to the top of the battery and the other wire to the bottom). Does it vibrate?
3. Attach the motor to the toothbrush using an adhesive, like hot glue or tape.
4. Connect the first wire to the appropriate face of the battery.
5. Attach the battery on top of the toothbrush using the adhesive.
6. Connect the second wire to the opposite face of the battery.
7. Decorate your bot, if desired.

### Tips:

• Try placing the wire on the tape or adhesive and then pressing the battery on top.
• There’s only one wrong way to make a brushbot—with an incomplete circuit! All other designs are fair game.
• What happens if you add things to your brushbot, like cardboard or pipecleaners?
• What happens if you put the motor on a different place on the brush?
• Disconnect your brushbot when you’re done enjoying it to save the battery.

## UD Connection

Robotics incorporates multiple disciplines of engineering, such as Mechanical Engineering, Electrical and Computing Engineering, and Computers and Information Science. Dr. Bert Tanner is one of our Mechanical Engineering faculty who works on planning and control of robot systems, mobile sensor networks, and more.