Spherical Definition and 1000 Threads

A sphere (from Greek σφαῖρα—sphaira, "globe, ball") is a geometrical object in three-dimensional space that is the surface of a ball (viz., analogous to the circular objects in two dimensions, where a "circle" circumscribes its "disk").
Like a circle in a two-dimensional space, a sphere is defined mathematically as the set of points that are all at the same distance r from a given point in a three-dimensional space. This distance r is the radius of the ball, which is made up from all points with a distance less than (or, for a closed ball, less than or equal to) r from the given point, which is the center of the mathematical ball. These are also referred to as the radius and center of the sphere, respectively. The longest straight line segment through the ball, connecting two points of the sphere, passes through the center and its length is thus twice the radius; it is a diameter of both the sphere and its ball.
While outside mathematics the terms "sphere" and "ball" are sometimes used interchangeably, in mathematics the above distinction is made between a sphere, which is a two-dimensional closed surface embedded in a three-dimensional Euclidean space, and a ball, which is a three-dimensional shape that includes the sphere and everything inside the sphere (a closed ball), or, more often, just the points inside, but not on the sphere (an open ball). The distinction between ball and sphere has not always been maintained and especially older mathematical references talk about a sphere as a solid. This is analogous to the situation in the plane, where the terms "circle" and "disk" can also be confounded.

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  1. M

    I Electric field inside & outside of a spherical shell

    Hi, I am reading Griffiths Introduction to electrodynamics. Currently I am solving problem 2.11 which asks to find an electric field inside and outside a spherical shell of radius R. Inside: $$\int{E \cdot da} = \frac{Q}{e_0} = |E|4\pi r^2 = \frac{Q}{e_0} = 0$$ The result is $$0$$ because we...
  2. kirito

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  3. per persson

    Potential in spherical shells

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  4. ergospherical

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  5. Jz21

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  6. D

    B Questions about the Paraxial region for a single spherical surface

  7. G

    I Range of projectile launched from a non-rotating spherical planet

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  8. M

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  9. L

    Why Is Deriving the Motion Formula for Hoops More Complex?

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  10. adhd_wonderer

    B Can Earth or any spherical object in space act as a particle collider?

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  11. birdhouse

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  12. Hak

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  13. P

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  14. milkism

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  15. Like Tony Stark

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  16. DrewPear

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  17. V

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  18. G

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  19. S

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  20. C

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  21. S

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  22. phos19

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  23. Addez123

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  24. G

    I Can Spherical Symmetry Be Achieved Without Varying Line Element?

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  25. cwill53

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  26. Povel

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  27. josephsanders

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  28. M

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  29. M

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  30. P

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  31. The Bill

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  32. L

    Image position and magnification for underwater spherical lens

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  33. JandeWandelaar

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  34. LCSphysicist

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  35. Delta2

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  36. LarryS

    I Is E/B = c for spherical EM Wave in Vacuum?

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  37. Ahmed1029

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  38. Philip Koeck

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  39. L

    Calculating Electric Potential and Energy in a System of Spherical Conductors

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  40. A

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  41. guyvsdcsniper

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  42. P

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  43. Salmone

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  44. J

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  45. H

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  46. guyvsdcsniper

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  47. VVS2000

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  48. L

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  49. Peter-

    I Calculating an increasing angle in Spherical Coordinates for a curve

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  50. L

    Maximum charge on a spherical capacitor

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