Fundamentals of Electric Circuits and Notation

Electronic Components: Passive and Active

  • Electronic systems are formed by using passive components in conjunction with active components.
  • Passive components will be studied throughout the initial chapters, while active components are primarily the subject of future courses.
Passive Components
  • Resistors: Introduced in Chapter 2, these are passive components used to provide resistance in a circuit. Features include:
    • Color bands for identification.
    • Resistance material, often carbon composition.
    • Insulation coating.
    • Leads for connection.
  • Capacitors: Introduced in Chapter 12. Examples and materials include:
    • Mica-foil construction (Mica-Foil-Mica-Foil stack).
    • Tantalum electrolytic capacitor (noted as polarized).
    • Mica capacitor.
  • Inductors: These passive components are introduced in Chapter 13.
  • Transformers: These passive components are introduced in Chapter 14.
Active Components
  • Transistors: A type of active component.
  • Integrated Circuits: Another primary type of active component.

Systems of Units

SI Fundamental Units

There are seven fundamental units in the International System of Units (SI). All other electrical and magnetic units are derived from these, with the exception of electric current, which is itself a fundamental unit.

  • Length: meter (mm)
  • Mass: kilogram (kgkg)
  • Time: second (ss)
  • Electric Current: ampere (AA)
  • Temperature: Kelvin (KK)
  • Luminous Intensity: candela (cdcd)
  • Amount of Substance: mole (molmol)
Electrical Units

Most electrical units are derived from the fundamental units listed above.

  • Current: ampere (AA)
  • Charge: coulomb (CC)
  • Voltage: volt (VV)
  • Resistance: ohm (WW)
  • Power: watt (WW)
Magnetic Units

All magnetic units are derived from the fundamental SI units.

  • Flux density: tesla (TT)
  • Magnetic flux: weber (WbWb)
  • Magnetizing force: ampere-turns/meter (At/mAt/m)
  • Magnetomotive force: ampere-turn (AtAt)
  • Permeability: webers/ampere-turns-meter (Wb/AtmWb/Atm)
  • Reluctance: ampere-turns/weber (At/WbAt/Wb)

Scientific and Engineering Notation

Very large and very small numbers are represented using scientific and engineering notation for clarity in electronics.

Scientific Notation
  • Definition: Expresses a quantity as a product of a number between 1 and 10 (one digit to the left of the decimal point) and a power of ten.
  • Examples:
    • 175,000=1.75×105175,000 = 1.75 \times 10^{5}
    • 0.000256=2.56×10−40.000256 = 2.56 \times 10^{-4}
    • 47,000,000=4.7×10747,000,000 = 4.7 \times 10^{7}
    • 0.000027=2.7×10−50.000027 = 2.7 \times 10^{-5}
    • 0.605=6.05×10−10.605 = 6.05 \times 10^{-1}
  • Calculator Instructions: Press SHIFT MODE. Press 7:SCI, then press 5 (digits). Enter the number and press =.
Engineering Notation
  • Definition: A specialized form of scientific notation used in electronics to express values of voltage, current, power, and resistance. It represents a number as a one-, two-, or three-digit number multiplied by a power of ten where the exponent is a multiple of three.
  • Examples:
    • 175,000=175×103175,000 = 175 \times 10^{3}
    • 0.000256=256×10−60.000256 = 256 \times 10^{-6} or 0.256×10−30.256 \times 10^{-3}
    • 47,000,000=47×10647,000,000 = 47 \times 10^{6}
    • 0.000027=27×10−60.000027 = 27 \times 10^{-6}
    • 0.605=605×10−30.605 = 605 \times 10^{-3}
  • Calculator Instructions: Press SHIFT MODE. Press 8:Norm, then press 1. Enter the number, press =, and then press the ENG key.

Metric Prefixes and Conversions

Engineering Metric Prefixes
  • Peta (P): ×1015\times 10^{15}
  • Tera (T): ×1012\times 10^{12}
  • Giga (G): ×109\times 10^{9}
  • Mega (M): ×106\times 10^{6}
  • Kilo (k): ×103\times 10^{3}
  • Milli (m): ×10−3\times 10^{-3}
  • Micro (m): ×10−6\times 10^{-6}
  • Nano (n): ×10−9\times 10^{-9}
  • Pico (p): ×10−12\times 10^{-12}
  • Femto (f): ×10−15\times 10^{-15}
Conversion Rules
  • Larger Unit to Smaller Unit: Move the decimal point to the right. A smaller unit requires a larger numerical value.
    • Example: 0.47 MW=470 kW0.47\,MW = 470\,kW
  • Smaller Unit to Larger Unit: Move the decimal point to the left. A larger unit requires a smaller numerical value.
    • Example: 10,000 pF=0.01 mF10,000\,pF = 0.01\,mF
Metric Arithmetic

When adding or subtracting numbers with metric prefixes, they must first be converted to the same prefix.

  • Example 1:
    • 10,000 W+22 kW10,000\,W + 22\,kW
    • Method A: 10,000 W+22,000 W=32,000 W10,000\,W + 22,000\,W = 32,000\,W
    • Method B: 10 kW+22 kW=32 kW10\,kW + 22\,kW = 32\,kW
  • Example 2:
    • 200 mA+1.0 mA200\,mA + 1.0\,mA
    • Method A: 200 mA+1,000 mA=1,200 mA200\,mA + 1,000\,mA = 1,200\,mA
    • Method B: 0.200 mA+1.0 mA=1.2 mA0.200\,mA + 1.0\,mA = 1.2\,mA

Selected Key Terms

  • Engineering notation: A system for representing any number as a one-, two-, or three-digit number times a power of ten with an exponent that is a multiple of three.
  • Exponent: The number to which a base is raised.
  • Metric prefix: A symbol that is used to replace the power of ten in numbers expressed in scientific or engineering notation.
  • Scientific notation: A system for representing any number as a number between 1 and 10 times a power of ten.