Instructions

9
Game and Knowledge in Electronics-Lab
Put together the first experiment; the LED light up. Then, swap the
connections so that the positive pole of the battery is connected to
the connector for LED7. Nothing lights up this time! This is because
an LED can only light up if it is connected the right way around.
There is no current if it is connected the wrong way around.
An LED has two different connections. They are called cathode
and anode. Only if the cathode is connected to the negative
pole and the anode to the positive pole of the LED, current
can flow and the light switches on. But the current must not
be too large. This will damage the LED. That’s why resistors
are installed in the LED strip, which are not indicated on the
top, but you can see them clearly on the inside. A resistor is a
component that conducts electricity less than a wire. In this case,
the resistors contain a thin layer of graphite. That’s the same
material as the one inside your pencil. They are also called
carbon-film resistors.
Please do not open up your modules, because something might
break. But you can see the resistors through the back wall.
They are named R1 to
R6 and have a small
inscription »151«. That
means that they have
150 ohms. That’s the
unit of impedance. The
larger this value, the
smaller is the current
that flows through the
LED.
4
LED the other way around
Warning!
The LED may sometimes be
plugged in the wrong way
round, though it will not
break. This is different with
other components. Some will
be damaged if the battery
is plugged in the wrong
way round. This especially
applies to the microcontroller
in your construction kit. It
must implicitly be plugged in
correctly!