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Physics vocabulary · Measurement and Units

Order of magnitude

Meaning in physics, with examples

nounCommon term

In physics, order of magnitude means: The approximate size of a number expressed as the nearest power of ten. Two values that differ by a factor of about ten differ by one order of magnitude.

In Turkish: büyüklük mertebesi, mertebe

How it is used

Used in estimates and in conversation: 'the nucleus is about five orders of magnitude smaller than the atom', 'your answer is out by an order of magnitude'. Order-of-magnitude estimates, also called Fermi problems, check whether a result is reasonable.

Example sentences

  1. Your answer is two orders of magnitude too big; did you forget to convert centimetres to metres?

  2. Make an order-of-magnitude estimate of the number of air molecules in this room.

Common collocations

  • orders of magnitude larger
  • order-of-magnitude estimate
  • out by an order of magnitude
  • within an order of magnitude
  • scientific notationA way of writing very large or very small numbers as a number between 1 and 10 multiplied by a power of ten, for example 3.0 × 10⁸ instead of 300,000,000.
  • significant figuresThe digits in a number that carry real information about its precision, counted from the first non-zero digit. For example, 0.00450 has three significant figures.
  • dimensional analysisA method of checking or building an equation by comparing the units or basic dimensions (mass, length, time and so on) on each side. Both sides of a valid equation must match.
  • SI unitsThe international system of measurement units used in science, based on seven base units such as the metre, kilogram, second, ampere and kelvin. SI comes from the French 'Système international'.

More terms: Measurement and Units

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