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

Example Sentences

See Examples For:

principal axis

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

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

On this floor there were also four smaller rooms used as commissioners' headquarters, manager's office, post-office, and lady manager's headquarters; also wide hallways at right angles to the principal axis of the building.

From Final Report of the Louisiana Purchase Exposition Commission by Louisiana Purchase Exposition Commission

Dihexagonal prism, consisting of twelve faces parallel to the principal axis and inclined to the planes of symmetry.

From Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 7 "Crocoite" to "Cuba" by Various