The Oxford Biblical Studies Online and Oxford Islamic Studies Online have retired. Content you previously purchased on Oxford Biblical Studies Online or Oxford Islamic Studies Online has now moved to Oxford Reference, Oxford Handbooks Online, Oxford Scholarship Online, or What Everyone Needs to Know®. For information on how to continue to view articles visit the subscriber services page.
Dismiss

### Related Content

#### More Like This

Show all results sharing these subjects:

• Science and technology
• Physics

GO

Show Summary Details

Overview

# dimensions

## Quick Reference

The product or quotient of the basic physical quantities, raised to the appropriate powers, in a derived physical quantity. The basic physical quantities of a mechanical system are usually taken to be mass (M), length (L), and time (T). Using these dimensions, the derived physical quantity velocity will have the dimensions L/T and acceleration will have the dimensions L/T2. As force is the product of a mass and an acceleration (see Newton's law of motion), force has the dimensions MLT−2. In electrical work in SI units, current, I, can be regarded as dimensionally independent and the dimensions of other electrical units can be found from standard relationships. Charge, for example, is measured as the product of current and time. It therefore has the dimension IT. Potential difference V is related to the current I and the power P by the relationship P = VI, where P is power. As power is force × distance ÷ time (MLT−2 × L × T−1 = ML2T3), voltage V is given by V = ML2T−3I−1.