Concentric

Concentric polygons.
Point T  is the common center
of six regular polygons.

Sector of concentric rings.
In Munsell's color system, a ring
represents a range of values
and saturations (chromas).

An archery target, featuring evenly spaced concentric circles that surround a "bullseye".

Concentric objects share the same center, axis or origin. Circles, tubes, cylindrical shafts, disks, and spheres may be concentric to one another. Notice that two objects can have equal radii and be concentric and different. For example, two different meridians of a terrestrial globe are concentric and congruent, their common center is a point that represents the earth center.

Examples

Evenly spaced circles of a target used in target archery or firearms is a familiar example of concentric circles.

Concentric cable is a cable type used in TN-C-S earthing systems where the combined neutral and earth core completely surrounds the live core(s). This minimizes the risk of completely cutting through the combined neutral and earth without first completely cutting through the live cores.

Concentric muscles contractions are those in which the muscle shortens.

External links

• Geometry: Concentric circles demonstration With interactive animation