A voltage, or electromotive force (emf), is the thing that makes it possible for electrons to move through a conductor. It's a very subtle force - a single volt is equivalent to the energy of a single electron, and has a huge range: we can measure a voltage from 0V to about 5V, or from 200V up to 2400V. That's V. You can see that it does have units of volts, but that's not really important, and you'll soon see why.
There's also an electronvolt (eV) , which is the energy it takes to move an electron through an electric field. This is typically in the range of about 10keV to 5MeV (and is equivalent to units of Joules or Watt's, or the equivalent to the volt on a volt-ohm meter.)
When we talk about currents, we're talking about changing potentials. So it's not actually a voltage that's doing it - it's the potential difference that's changing, and that's measured in Volts, or Volt-Amps (V/A). An amp (ampersand) is a unit of Amperes (A), or Coulombs per second (C/s). In the same way, Amperes is also the SI unit for current, so we'll be using both Amp (Ampersand) and Amps (Ampersand) interchangeably. This is a bit confusing (we'll come back to this later), and we should point out that Amps are used in some electronic circuits, but Amperes are the units used in circuit design.
In electronics, a signal is a thing that tells us what is going on. If you turn a light on then it is a signal. If you connect a power supply to a lamp and it lights up, it is a signal. If you connect a speaker to a sound system and play a CD, it is a signal. If you stick a cat in a microwave oven and it hisses at you, it is a signal.
The path to electronics mastery is a long one. This article is the first of a long series aimed at beginners, and is written in the same style as the rest of the site. The next article will cover basic circuit theory - (next page)
The reason for the low value capacitor is to keep the scope probe high in impedance. For the sake of completeness, here is another, higher value, example. This time, it is a 10uF capacitor, which might be a little too high for this circuit. The higher value may be a better choice for this circuit, but it will be easier to see the input signal with a smaller value. The 1000uF value is chosen because it is the lowest value available from AV, in their standard range. In the past, I've used values up to 1000uF, but that was before they were widely available.
The body of the capacitor is then soldered in place, and now your capacitor is complete. It may be difficult to see, but it may have a label which indicates the number of plates and some other dimensions of the capacitor.
If you're using one of the starter kits, take a look at the small 'Tips and Tricks' PDF which comes with it - it can be found under the 'Support' sub-menu on the 'My Arduinos' page. This guide is a great reference for when you're ready to 'go pro'. 827ec27edc