Overview
This lesson introduces SI units used in engineering and explains engineering notation, a modified form of scientific notation commonly applied in technical fields.
SI Units in Engineering
- SI units (International System of Units) were established in 1960 for universal measurement standards.
- Key SI units in this course include: meter (length), kilogram (mass), Kelvin (temperature), and mole (amount of substance).
- Charge is measured in coulombs (C).
- Electric current is measured in amperes (A).
- Voltage is measured in volts (V).
- Power is measured in watts (W).
- Resistance is measured in ohms (Ω).
- Capacitance is measured in farads (F).
- Inductance is measured in henrys (H).
Engineering Notation
- Scientific notation simplifies writing very large or small numbers (e.g., 1.2 × 10⁻⁸ F).
- Engineering notation uses powers of three (10⁻⁹, 10⁻⁶, 10⁻³, 10⁰, 10³, etc.) for easier use with metric prefixes.
- Common prefixes: femto (f, 10⁻¹⁵), pico (p, 10⁻¹²), nano (n, 10⁻⁹), micro (μ, 10⁻⁶), milli (m, 10⁻³), kilo (k, 10³), mega (M, 10⁶), giga (G, 10⁹).
- Example: 330,000 Ω = 330 kΩ or 0.33 MΩ; 0.000000012 F = 12 nF or 0.012 μF.
- Always write values using the most suitable metric prefix, usually keeping numbers between 1 and 999.
Key Terms & Definitions
- SI Units — International measurement system for standardizing physical quantities.
- Coulomb (C) — Unit of electric charge.
- Ampere (A) — Unit of electric current.
- Volt (V) — Unit of electric potential (voltage).
- Watt (W) — Unit of power.
- Ohm (Ω) — Unit of electrical resistance.
- Farad (F) — Unit of capacitance.
- Henry (H) — Unit of inductance.
- Engineering Notation — Way of writing numbers using powers of three and metric prefixes.
Action Items / Next Steps
- Memorize the SI base units and their symbols.
- Learn and practice the engineering notation prefixes and their associated powers of 10.
- Prepare to use these units and prefixes in computations and future lessons.