-As you may have heard at one time or another in your life "electricity takes the path of least resistance", this is very true and electricity is lazy! The best analogy that I have heard over the years is that electricity is like water, yes water. Let's say we have a water hose with a valve on the end. When you open the valve you have water pouring out. The amount pouring out is considered Volume (Amperage), and the amount of force behind it can be the Pressure (Voltage), the slowing of the water in the hose can be related to Friction (Ohm's) or resistance.
-In a wire the analogies still applies. When you here someone talk of Voltage in a circuit or talking of someone being zapped by 60,000 volts this is not necessarily bad. Voltage isn't your enemy, its amperage! Amperage will kill you real quick even with lower voltages. The primary measurement of electricity is done in Current and Amps. The current measures the Amperage in a circuit, and the Volts measures the pressure. The more current the more amps that exist, the more pressure in the circuit the more Voltage that exist.
-Be familiar with these terms.
Amps- A measurement of the currents flow or rate of flow. In a PC the Hard Drive will typically use 2.0 Amps to get started and about .35 for typical spin operation.
Ohm's-Measures a conductors resistance to electricity. In the typical PC you need 20 Ohms of resistance for electricity to flow.
Volts- Measures the electrical pressure in a circuit. The Power Supply on your system will produce for levels of voltages such as +5, -5, +12, -12.
Watts-Measures the amount of power in a circuit. You will also see the Power supply in watts ranging from 200-600V.
Continuity- Indicates the existence of a complete circuit. The DIN (PS/2) connector for you mouse or keyboard can have as much as 5 Volts. This continuity can be measured with a multimeter.