Powers of Ten

• What is the diameter of an atom approximately?

  $10^{-10} \text{ m}$
• What is the width of a galaxy approximately?

  $10^{21} \text{ m}$
• What is the difference in powers of ten between the diameter of an atom and the width of a galaxy?

  31 powers of ten
• What are powers of ten?

  Numbers achieved by multiplying 10 by itself
• What are the prefixes for certain powers of ten?

  • k (kilo) = $10^3$
  • M (mega) = $10^6$
  • G (giga) = $10^9$
  • T (tera) = $10^{12}$

  
• What is the conversion of 5 kN in newtons?

  5000 N
• What is the conversion of 7 nC in coulombs?

  $0.000000007 \text{ C}$
• What is the relationship between Joules (J) and electronvolts (eV)?

  1 eV = $1.6 \times 10^{-19} \text{ J}$
• How do you convert Joules to electronvolts?

  Divide by $1.6 \times 10^{-19}$
• How do you convert electronvolts to Joules?

  Multiply by $1.6 \times 10^{-19}$
• What is the conversion factor between Joules and kilowatt-hours?

  1 kWh = 3.6 × 10$^6 \text{ J}$
• How do you convert Joules to kilowatt-hours?

  Divide by $3.6 \times 10^{6}$
• How do you convert kilowatt-hours to Joules?

  Multiply by $3.6 \times 10^{6}$
• What are common exam tips for powers of ten?

  • Familiarize with large and small numbers
  • Avoid common mistakes with prefixes
  • Practice conversions between units
• What is the ionisation energy of hydrogen in Joules?

  $2.176 \times 10^{-18} \text{ J}$
• How do you calculate the ionisation energy of hydrogen in eV?

  Divide $2.176 \times 10^{-18} \text{ J}$ by $1.6 \times 10^{-19} \text{ J}$
• What is the ionisation energy of hydrogen in eV?

  13.6 eV