Overview
The lecture covers units of length from nanometers to kilometers, conversion methods between these units, and the relative sizes of common small objects.
Units of Length and Scale
- Common length units: nanometers (nm), micrometers (μm), millimeters (mm), centimeters (cm), meters (m), and kilometers (km).
- Each unit is 1,000 times bigger or smaller than the next adjacent unit on the scale.
- 1 cm = 10 mm, and 1 m = 100 cm.
Converting Between Units
- To convert to a larger unit, divide by 1,000 for each step up the scale (e.g., mm to m: divide by 1,000).
- Example: 6 mm = 0.006 m = 6 × 10⁻³ m.
- To convert to a smaller unit, multiply by 1,000 for each step down the scale (e.g., mm to μm: multiply by 1,000).
- Example: 6 mm = 6,000 μm = 6 × 10³ μm.
- For units not next to each other (e.g., nm to mm), convert stepwise or use the total factor (e.g., divide by 1,000,000).
Relative Sizes of Objects
- Atoms: 0.1–0.5 nm.
- Molecules (like glucose): about 1 nm.
- Viruses: about 100 nm.
- Bacteria: about 1 μm.
- Animal/plant cells: 10–100 μm.
- Human hair: about 100 μm.
- Naked eye can see down to about 100 μm; light microscopes to 500 nm; electron microscopes to 0.1 nm.
Converting with Centimeters
- 1 cm = 10 mm; 1 m = 100 cm.
- To convert cm to mm, multiply by 10; to m, divide by 100.
- Example: 30 cm × 10 = 300 mm × 1,000 = 300,000 μm × 1,000 = 300,000,000 nm = 3 × 10⁸ nm.
Key Terms & Definitions
- Nanometer (nm) — one billionth of a meter (1 nm = 10⁻⁹ m).
- Micrometer (μm) — one millionth of a meter (1 μm = 10⁻⁶ m).
- Millimeter (mm) — one thousandth of a meter (1 mm = 10⁻³ m).
- Centimeter (cm) — one hundredth of a meter (1 cm = 10⁻² m).
- Meter (m) — base unit of length in the metric system.
- Kilometer (km) — one thousand meters (1 km = 1,000 m).
Action Items / Next Steps
- Practice length unit conversion questions and review the associated lesson on the linked platform.