CONFIANZA SOCIAL
VIII. CONTENIDOS
10–15 femto f one-quadrillionth
10–12 pico p one-trillionth
10–9 nano n one-billionth
10–6 micro µ one-millionth
10–3 milli m one-thousandth
10–2 centi c one-hundredth
100 Whole units need no prefix or symbol.
103 kilo k thousand
106 mega M million
109 giga G billion
1012 tera T trillion
Table 1-3. The Powers of Ten Used in Electronics Have Equivalent Prefixes and Symbols
EXAMPLE SOLUTION
Write the following quantities using the nearest standard symbol as listed in Table 1-3.
Practice Problems Practice Problems
Write the following quantities using the nearest standard symbol listed in Table 1-3.
1. 56 × 103 Ω
2. 22 × 10–4 A
3. 500 × 104 W
4. 12 × 10–6 s
5. 1.75 × 108 Hz
Answers to Practice Problems
We can also convert from one prefix to another through the following procedure:
1. Replace the given prefix with the equivalent power of ten.
2. Relocate the decimal (left or right) while you adjust the power of ten.
3. When the power of ten matches the value of the desired prefix, replace it with the prefix.
EXAMPLE SOLUTION
Express 0.1 milliamperes as an equivalent number of microamperes.
EXAMPLE SOLUTION
First, we replace the given prefix with the equivalent power of ten as follows:
a. 125 × 10–3 V b. 5 × 103 Hz c. 0.001 × 10–11 F d. 10.2 × 10–9 s e. 3300 × 105 Ω
EXAMPLE SOLUTION
a. 125 mV b. 5 kHz
c. 0.01 pF d. 10.2 ns
e. 330 MΩ
1. 56 kΩ 2. 2.2 mA 3. 5,000 kW
4. 12 µs 5. 0.175 GHz
0.1 mA = 0.1×10–3 A
Next, we move the decimal until the power of ten matches the micro prefix (i.e., 10–6). In this case, we will have to move the decimal point three places to the right:
Finally, we substitute the equivalent prefix:
1. Write the standard prefix for each of the following powers of ten:
2. Write the following quantities using the nearest standard prefix as listed in Table 1-3.
3. Write the following quantities using the nearest standard symbol as listed in Table 1-3.
4. Express the following quantities in the forms indicated.
a. Express 12,500 hertz as kilohertz.
b. Express 0.0005 × 10–4 farads as microfarads.
c. Express 0.0025 milliseconds as microseconds.
d. Express 390 milliamperes as amperes.
a. 10–3 b. 106 c. 109
d. 10–12 e. 10–2
a. 22.5 × 10–6 F b. 250 × 105 Hz
c. 27 × 10–5 H d. 122 × 10–4 s
a. 220 × 10–5 H b. 2500 × 10–4 W
c. 0.008 × 10–7 F d. 5.99 × 104 Hz 0.1×10–3 A = 100×10–6 A
100×10–6 A = 100 µA
Exercise Problems 1.4 Exercise Problems 1.4
Chapter Summary
• Electronics is a field with an incredibly wide range of applications. Electronic devices are used as important tools in most other career fields. Due to the wide range and endless numbers of electronics applications in today’s world, there is also a vast range of career opportunities for electronics technicians. Although the details of the various jobs performed by electronics technicians may vary, they all require a thorough under-standing of basic electronics components, fundamental mathematics, and electronics principles.
• It is important for an electronics technician to be able to identify an electrical or elec-tronic component by its physical appearance. This task is complicated by two charac-teristics of these components. First, there is a wide range of physical shapes and sizes for a given type of component. Second, some radically different components look fundamentally similar. The more experience a technician has with a wide variety of electronic components, the easier identification becomes.
• This chapter discussed the composition of matter. Matter is composed of a number of progressively smaller entities or building blocks. A sample quantity of any given matter can be roughly classified as a mixture, a compound, or an element. A mixture is composed of two or more compounds or elements. A compound is composed of molecules. Molecules are formed when two or more atoms of different elements are chemically combined.
• We divided the molecule into its component atoms and then studied the atom itself.
The atom consists of a nucleus made of densely packed particles and orbited by smaller particles. The primary particles in the nucleus are protons and neutrons.
Protons have a positive charge. Neutrons have no charge. The orbiting particles are called electrons. They have a negative charge. Although the positive charge of the proton is equal in magnitude to the negative charge of an electron, the proton has 1,836 times more mass than the tiny electron.
• A model of the atom was studied that showed how the electron orbits occurred at defi-nite “altitudes” called energy levels. Several closely related orbits are often collectively referred to as a shell. The energy level of an electron determines its specific orbit. If an electron moves to a lower orbit, it will release energy. Similarly, if an electron absorbs sufficient energy, it will move to a higher orbit.
• Electrons in the outer orbit are called valence electrons. If a valence electron absorbs enough energy, it can escape the orbit of the atom and become a free electron. With no external force, the movement of free electrons in a substance such as copper wire is essentially random. However, if an external field that causes one end of the wire to be positive and the other end negative is applied, then the free electrons no longer travel in random directions. The external charges cause the free electrons to drift toward the positive end of the wire. This directed flow of electrons is called electron current flow.
• Current flow and charge are only two of many electrical quantities that must be measured and expressed in the field of electronics. This chapter presented several other fundamental quantities, their units of measurement, an abbreviation for each quan-tity, and a symbol for each unit of measurement.
• Many of the quantities measured and expressed in electronics require the use of extremely small and extremely large numbers. To simplify the expression and manipu-lation of these numbers, we use some form of technical notation. Three forms were discussed in this chapter: powers of ten, scientific notation, and engineering notation.
Scientific notation and engineering notation are just special instances of the more general powers-of-ten notation. Scientific notation requires that all numbers be expressed as a number between one and ten times an appropriate power of ten. Engi-neering notation is simply an application of powers of ten. Here, the power of ten must be zero or an exponent that is evenly divisible by three. The base number is often between 1 and 999.
• To add or subtract numbers that are expressed in a power-of-ten format, the decimal point on either or both numbers must be adjusted until the exponents of the power of ten are identical. Addition or subtraction of the base numbers is then performed as usual. The power of ten for the result will be identical to the common exponent used for
the two operands. Multiplication and division of numbers expressed in a power-of-ten form are more straightforward. Perform the calculation on the base numbers as usual.
For multiplication, the power of ten in the result will be the sum of the multiplicand and multiplier powers of ten. For division, the power of ten for the result will be the differ-ence of the divisor and dividend exponents (dividend exponent minus divisor expo-nent). Powers-of-ten calculations may be done quickly with an electronic calculator.
• The use of prefixes as substitutes for certain specific powers of ten greatly simplifies the written and spoken expression of electronic quantities. Those powers of ten that are even multiples of three are the ones most often substituted with a prefix.
Review Questions Review Questions