principal axis

American  

noun

1. Optics. a line passing through the center of the surface of a lens or spherical mirror and through the centers of curvature of all segments of the lens or mirror.

2. Physics. one of three mutually perpendicular axes of a body about which the moment of inertia is maximum or minimum.

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principal axis British  

noun

1. the line passing through the optical centre and centres of curvature of the faces of a lens or a curved mirror

2. any of three mutually perpendicular axes about which the moment of inertia of a body is maximum

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Etymology

Origin of principal axis

First recorded in 1875–80

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Example Sentences

See Examples For:

principal axis

To determine this ratio we consider its value for a vertex on the principal axis.

From Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 6 "Geodesy" to "Geometry" by Various

The axis which contains the foci is called the principal axis, and the intersection of the axis with the curve is called the vertex of the curve.

From An Elementary Course in Synthetic Projective Geometry by Derrick Norman Lehmer

This constant sum or difference equals in both cases the length of the principal axis.

From Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 6 "Geodesy" to "Geometry" by Various

The principal axis follows a curved line from the Maritime Alps towards the north-east by Mont Blanc and Monte Rosa and St. Gotthard to the mountains overlooking the Engadine.

From The Beauties of Nature and the Wonders of the World We Live In by Sir John Lubbock

The ray AC, parallel to the principal axis, will pass through the lens and emerge as DE.

From General Science by Bertha M. Clark

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