Powering a circuit: electricity
Tame electrical waves and currents.
6. Voltage and current
We have mentioned these terms a few times already, without having them explained properly.
Imagine a ball being thrown through the air.
- Voltage is the speed the ball is travelling. This is measured in Volts. It's symbol is a capital V.
- Current is the size of the ball being thrown. This is measured in Amperes (or Amps for short). Its symbol is a capital A.
All DC electricity can be thought of as having a voltage and a current. In order to determine what these are, you can use a multimeter.
Measure the voltage of a battery
Place the red probe on the positive terminal of the battery. Place
the black probe on ground (or "minus") terminal of the battery. You
should get a reading close to its nominal value, e.g. 9V.
If you reverse the probes of the multimeter you will notice that the
meter will give you a negative voltage reading. The reason for this is
that DC electricity has a positive voltage and a ground voltage. The reading on the multimeter is actually the black probe's voltage level subtracted from the level of the red probe.