Colour Selector - Maker Factory 1968203 Manual

5

Colour selector

Behind door number 5 you will find
a second cable. Use it to convert your
circuit so that the red LED is not switched
on until you press the push button. At
the same moment the green LED will go
out. With this switch you can change the
colour: pressed = red, released = green.
Once the switch is closed, both LEDs will
be connected in parallel. One might think
that current would flow through both and
that both would glow. This is actually the
case when the same LEDs are used. But
there' s a big difference here. The green LED
needs more current than the red LED. If
the red LED is now switched on, the LED
voltage drops to such an extent that the
green LED can no longer shine.
Voltage, resistance and current
You may already know that the battery is still new, it will have a
electrical voltage is measured voltage of 9 V. The green LED
in volts (V). The battery is 9 V. needs about 2 V. That leaves 7V
Resistance is measured in ohm for the resistor. And then you can
do the calculation like this:
(kΩ) or kilo-ohm (1 kΩ = 1,000
Ω). But there is another very
Current = voltage/resistance
important measurement: The
Current = 7 V/10,000 Ω
electrical current is measured in
amperes (A) or in milliamperes
Current = 0.0007 A =
for small currents (mA = 1/1000
0.7 mA
A). All these names come from
famous researchers who were the
That's not much, there is a flow
first to research electricity about
of only 0.7 mA, although the LED
200 years ago: Alessandro Volta,
can handle a current of 20 mA.
Georg Simon Ohm and André-
But the battery lasts for a very long
Marie Ampère.
time! It usually has a capacity of
A measuring device could be 500 mAh (500 mAh), so it could
used to measure how much deliver 500 mA for one hour or
current flows through the LED. But 1 mA for 500 hours. Your lamp
you can also calculate it, if you will therefore glow at 0.7 mA for
know the voltage of the battery about 700 hours, which is about
and the voltage of the LED. If the a month long.