Lesson plan

Area density

The area density (also known as areal density, surface density, superficial density, column density, or density thickness) of a two-dimensional object is defined as the quotient of mass by area. The SI derived unit is the "kilogram per square metre" (unit symbol kg·m −2 ). In the paper and fabric industries, it is called grammage and is expressed in grams per square meter (g/m 2 ); for paper in particular, it may be expressed as pounds per ream of standard sizes ("basis ream"). A generalized areic quantity is defined as the quotient of a generic physical quantity by area, such as surface charge density or areic electric charge. A related area number density can be defined by replacing mass by number of particles or other countable quantity.

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Article summary

The area density (also known as areal density, surface density, superficial density, column density, or density thickness) of a two-dimensional object is defined as the quotient of mass by area. The SI derived unit is the "kilogram per square metre" (unit symbol kg·m −2 ). In the paper and fabric industries, it is called grammage and is expressed in grams per square meter (g/m 2 ); for paper in particular, it may be expressed as pounds per ream of standard sizes ("basis ream"). A generalized areic quantity is defined as the quotient of a generic physical quantity by area, such as surface charge density or areic electric charge. A related area number density can be defined by replacing mass by number of particles or other countable quantity.

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