sine wave

A sinusoidal waveform, a sine wave is perhaps best explained and illustrated using electrical current. Current is the flow of electrons through a metallic circuit, with the direction of flow being from positive (+) pole to negative (–) pole. Direct current (dc) travels in one direction, only, while alternating current (AC) travels in both directions across the circuit. A continuous flow of AC current travels first in one direction and then reverses polarity and flows in the opposite direction. The number of times the polarity reverses direction per second is termed the frequency (f or ), and is measured in cycles per second (cps) or, in more contemporary terms, Hertz (Hz). Voltage (V) is the measure of the electromotive force (emf) and potential difference between the positive and negative ends of the circuit (or a battery).

Voltage, i.e., signal strength, or amplitude, is expressed as +V and –V, depending on the direction of the current, with examples being +3V and –3V, or +1.5V and –1.5V. The frequency of the continuous AC

waveform is the number of times per second that the waveform makes a complete cycle from zero voltage (0V) to its maximum positive voltage (+V), back to zero (0V), to its maximum negative voltage (–V), and back to zero (0V), as illustrated in Figure S-2.

• Class 3
• Class 4
• Class 4/5
• Class 5
• Class A ATM traffic
• Class A cable
• Class A IP address
• Class B ATM traffic
• Class B cable
• Class B IP address
• Class C ATM traffic
• Class C cable
• Class C IP address
• CLASS (Custom Local Access Signaling Services)
• Class D ATM traffic
• Class D ATM traffic
• Class D cable
• Class D IP address
• Class D IP address
• Class E cable
• Class E IP address
• Class F cable
• Classical IP over ATM (Classical Internet Protocol over Asynchronous Transfer Mode)
• Classless Inter-Domain Routing (CIDR)
• class of service (CoS)