Units, Dimensions, and Standards INTRODUCTION

SCIENTIFIC NOTATION AND METRIC PREFIXES1. Scientific NotationVery large or very small numbers are conveniently written as a number multiplied by 10raised to a power:100 = 1×10×10 = 1×10 210 000 = 1×10×10×10×10 = 1×10 40.001 = 1×10 31500 = 1.5 ×10 30.015 = 1.5 ×10 2Note that in the SI system of units, spaces are used instead of commas when writing largenumbers. Four-numeral numbers are an exception. One thousand is written as 1000, while tenthousand is 10 000.2. Metric PrefixesMetric prefixes and the letter symbols for the various multiples and submultiples of 10 arelisted in Table 1-1, with those most commonly used with electrical units shown in bold type. Theprefixes are employed to simplify the writing of very large and very small quantities. Thus,1000 can be expressed as 1 kilo-ohm, or 1k. Here kilo is the prefix that represents 1000, and kis the symbol for kilo. Similarly, 1×10 3 A can be written as 1 millilampere, or 1 mA.TABLE 1-1 SCIENTIFIC NOTATION AND METRIC PREFIXESValue Scientific Notation Prefix Symbol1 000 000 000 000 10 12 tera T1 000 000 000 10 9 giga G1 000 000 10 6 mega M1 000 10 3 kilo k100 10 2 hecto h10 10 deka da0.1 10 1 deci d0.01 10 2 centi c0.001 10 3 milli m0.000 001 10 6 micro µ0.000 000 001 10 9 nano n0.000 000 000 001 10 12 pico p3. Engineering NotationAs already discussed, 1 k is 1×10 3 , and 1 mA is 1×10 3 A. Note also from Table 1-1that 1×10 6 is expressed as 1 M, and 1×10 6 A can be written as 1 µA. These quantities, and most3