Units of Length and Conversion

In this lecture, we explore various units of length, their scale, and how to convert between them. Additionally, we examine examples of small entities like atoms and cells to understand their size in context.

Units of Length

• Nanometers (nm)
• Micrometers (µm)
• Millimeters (mm)
• Meters (m)
• Kilometers (km)

Scale Explanation

• Each unit is 1,000 times bigger or smaller than the adjacent unit.
  • Example:
    • 1 km = 1,000 m
    • 1 nm = 0.001 µm

Converting Between Units

Converting to Larger Units

• General Rule: Divide by 1,000 for each step up the scale.
• Example: Convert 6 mm to meters:
  • 6 mm / 1,000 = 0.006 m or 6 x 10^-3 m

Converting to Smaller Units

• General Rule: Multiply by 1,000 for each step down the scale.
• Example: Convert 6 mm to micrometers:
  • 6 mm x 1,000 = 6,000 µm or 6 x 10^3 µm

Multi-step Conversion Example

• Example: Convert 340 nm to millimeters:
  • 340 nm / 1,000 = 0.34 µm
  • 0.34 µm / 1,000 = 0.00034 mm or 3.4 x 10^-4 mm

Understanding Sizes

• Atoms: ~0.1 to 0.5 nm
• Molecules (e.g., glucose): ~1 nm
• Viruses: ~100 nm
• Bacteria (small cells): ~1 µm
• Animal/Plant Cells: 10-100 µm
• Human Hair: ~100 µm

Visible Range

• Naked Eye: Can see down to ~100 µm (width of human hair)
• Light Microscope: Down to ~500 nm
• Electron Microscope: Down to ~0.1 nm

Centimeters

• Position in Scale: Between millimeters and meters
• Conversion:
  • 1 cm = 10 mm
  • 100 cm = 1 m

Conversion Example

• Example: Convert 30 cm to nanometers:
  • 30 cm x 10 = 300 mm
  • 300 mm x 1,000 = 300,000 µm
  • 300,000 µm x 1,000 = 300,000,000 nm or 3 x 10^8 nm

Practice and Further Learning

• For additional practice and detailed lessons, refer to the provided platform link in the video description for exercises and to check understanding.