Agorobots - Tuesday plan

What is a robot?

You probably already know a robot are when you see it:

Not robots:

So what is special about R2D2, Feelin' Crabby, and Sojourner?

How do you build a robot?

People have been trying to build robots for thousands of years, but progress was very limited before one modern invention: electronics. Using electronic circuits, it is possible to build tiny machines that can do extremely complex tasks, from addition and multiplication to intelligent decision-making. Electronics can be linked to the physical world through a variety of sensors and motors to create machines that interact with their environment in every possible way. This is why we have to learn a little bit about electronics before we can start building robots.

Water as a model for electricity.

Electricity is like water in a river; it flows downhill:

A battery is a pump that can maintain a difference in water level:

A resistor is a place where the river is full of rocks. Water has a tough time flowing past it, so the level can drop quickly.

A diode is a waterfall; a place where the level of the water suddenly changes by a certain amount.

A simple electronic circuit.

First of all, the battery gives us a voltage difference of 6 volts, but we want 5, so we'll use a diode (a waterfall, remember) to drop the level by a little bit (about 1 volt):

Now, we'll let the electricty flow across a resistor and another diode, then return to the battery:

The second diode is special: as electricity flows over it, it emits light! This is called a light-emitting-diode or LED. Here's what the circuit looks like as a river:

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