What Is a Circuit?
A circuit is a loop made up of different components — like your LED — that allows electricity to flow.
Circuits must have a power source, a load like your LED, and a conductive material that allows the electrical energy to flow.
Ask campers to try to identify the power source, load, and conductive material from one of the electrical items they identified earlier.
The loop must be closed for a circuit to work. Your LED will light up when electricity flows from the battery through the light and back to the battery.
The electricity in a circuit must flow in the right direction. Power flows from the negative (-) side of the battery (anode) to the positive (+) side of the battery (cathode). Some loads, like LEDs, must be connected in the right direction for them to work.
Want more information on circuits? Try this presentation.
Build a Circuit
Gently pop the Battery Pack out of the Shake It Board. Place a battery into your battery pack with the smooth positive side facing up. Turn the switch to “on.”
Link 2-3 paper clips together into a chain. Make three chains total.
Hook one paper clip chain to the battery pack on the positive (red) side, taking care to touch the metal tinned area. If desired, use a bit of Maker Tape to strengthen the connection. Connect the other side of the paper clip chain to the positive (red) side of the LED.
Repeat with another chain of paper clips, connecting the negative (white) side of the battery to the negative (white) side of the LED. (Figure 2a)
Turn on the switch. Your LED should light up. Note: You may need to wiggle or pull on the paper clip chains a bit to get a good connection. You have just created a simple series circuit, a loop where the whole current flows through each component.
Let’s test the properties of different materials.
Turn off the battery pack. Unhook the chain from the red (positive) side of the battery pack. Attach the third paper clip chain to the battery pack. Turn on the battery pack.
To test items for conductivity, touch the unhooked chains to the item. If the LED lights up it conducts electricity. (Figure 2b) Test the maker tape, a pencil, a paper clip, an eraser, cardboard, a cup of water, yourself, etc.
On the board (or elsewhere) make a list of things that conduct electricity and things that don’t. What do they have in common, if anything?
Let’s add a tilt switch.
Turn off the battery pack. Place the tilt switch between the two unlinked paper clip chains, connecting to the white, tinned (shiny) openings. Turn on the battery pack. (Figure 2c)
Move the tilt switch to turn the LED on and off. In what ways could a tilt switch be used in your inventions? What other things could you use as a switch?
If time permits, or if you have more advanced campers, build a parallel circuit.
Have campers partner up. Ask them if they can add a second or third LED to the circuit. (If working virtually, have campers use traditional LEDs rather than chip LEDs.)
If campers attempt to simply add another LED to the chain, they will quickly run out of power to light them all. This is the series circuit where all the load elements are connected in a single path. (See glossary for further information.)
Build a parallel circuit instead. Use paper clips to make a circuit where each LED has its own loop back to the battery. (Figure 2d)