sents the duration of the cycle and can be expressed as a fraction of the frequency. Thus, if T represents the period of a signal and f is the signal's frequency, then T = 1/f. We can also express frequency in terms of the period of a signal: f = 1/T. In Figure 2.2 we note that the sine wave whose period is 1 S has a fre- quency of 1/1 or 1 Hz. Similarly, the second sine wave whose period is 0.5 Chapter Two one cycle per second Figure 2.2 Oscillating sine waves at different fre- quencies. two cycles per second seconds S has a frequency of 1/0.5, or 2 Hz. The period and the frequency of a signal are inversely proportional to one another. Thus, as the period of a signal decreases, its frequency increases. Wavelength The period of an oscillating signal is also referred to as the signal's wave- length, denoted by the Greek lowercase symbol lambda (A). The wave- length of a signal can be obtained by dividing the speed of light (3 X 108 m/s) by the signal's frequency in hertz. In actuality, the speed of light is 299,792,458 m/s. However, since the goal of this book is to explain the transmission of information over fiber optics and not to teach physics, we will round the speed of light to 3 X 108 m/s. Thus, we can denote the wavelength of a signal for either radio or light waves as follows: Understanding Light Note that you can adjust the numerator and denominator of this equa- - tion. In SO doing, you can adjust the frequency from hertz (Hz) to kilo- hertz (kHz), megahertz (MHz), gigahertz (GHz), and terahertz (THz). As a refresher for those of you who may be a bit rusty remembering prefix- es for the power of 10, Table 2.1 lists nine common prefixes and their meanings. Thus, the use of GHz represents billions of cycles per second, while MHz refers to millions of cycles per second, and kHz is used to refer to thousands of cycles per second. Wavelength can be expressed in terms of Hz, kHz, MHz, GHz, and THz as follows: 0.0003 f(MHz) f(GHz) f(THz) Because wavelength is expressed in terms of the speed of light divided by