Find the light-emitting diodes in your kit. They look like the
picture at right.
Write a description of
the various things the light-emitting diodes do.
Here is a list of things to try -- but probably you have done them all
already!
. The triangle is meant to indicate that
current flows only one way, and the curvy arrow is supposed to
represent light being made. The bidirectional L.E.Ds (that give
different colors for different directions of the current) are
actually two diodes in one container.We have now met several electrical devices (most of them in the section on the direction of current):
A light bulb turns
electrical energy into heat and light no matter which way the
current flows.
The behavior of a
motor does depend on the direction of the current: when you reverse
the current, it turns the other way.
The buzzer in your
kit is a very sophisticated device -- there is even a transistor in
there -- but fundamentally it also is a kind of electrical magnet.
Transistors only work with one direction of current, and so this
device is only works when the battery is connected the right
way.
The light emitting
diode is a relative of a transistor. Their sensitivity to the
direction of the current is inherent to the way they work; when you
connect them to a battery the wrong way, no current flows and
nothing happens at all.
The light bulb is an example of a "linear" device. It will operate over a wide range of applied voltage; increasing the voltage causes the current to increase, and the light bulb gets brighter. The light emitting diode is a "nonlinear" device: it doesn't do anything at all (and no current flows through it) when the voltage is below 1.6 V; with a higher voltage the current increases rapidly.
Check the box when you are
done:
Next:
Electrical energy and the capacitor