Polarity

Materials:

  • Two (2) Wires
  • Batteries Block
  • Bi-color LED Block
  • LED Block
  • Lightbulb Block

Imagine walking down a path. You could stop in your tracks, then turn around and go back the way you came. Electricity cannot do this. Electricity travels in one direction, through a circuit of conductive materials, from the positive side of a battery to the negative side of the battery.

Make a circuit with the Batteries Block and Bi-color LED Block. What color is your bi-color LED glowing? Is it red? Is it green? Trace the pathway from the red (positive) side of the battery to the bi-color LED. Is it connected to the red wire? Or the green wire? What happens if you reverse the direction the bi-color LED is connected to the batteries in your circuit – if it is red to red, try making it red to green or vice versa.

What do you notice about the color of the bi-color LED? How do you make it green? How do you make it red?

Build a circuit with the Lightbulb Block in place of the Bi-color LED Block. Now, disconnect the circuit and turn the Lightbulb Block around so the electricity flows through it in the other direction - just as you just did with the Bi-color LED Block. Do you notice anything change? Or, does the light work exactly the same either way?

Some components behave differently depending on which way electricity flows through them. Components like this are "polarized."

A bi-color LED is a polarized HAPPEN component. Polarity matters for the bi-color LED. Always know which way the path of electricity is flowing through your circuit; draw it in your schematics. Electricity flows from the positive side of the battery to the negative side.


Build a circuit with the regular LED Block instead of the Bi-color LED Block. Be careful this time to connect the positive side of the LED to the positive side of the batteries.

What do you notice? What happens?

Now, disconnect the LED Block and then connect it back into the circuit so that the electricity flows through it in the other direction. What happens? What doesn't happen? Does polarity matter with the LED? How is the LED different from the bi-color LED? How is it the same?

An LED is a polarized HAPPEN component. Some components can only happen with electricity flowing through in one direction.