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abstraction > mathematical concept > number > quantity > length > radius

radius
subject			fact

radius	is a kind of length
length	has unit length unit
number	has value

Kinds of radius :

• Bohr radius (12 facts) (a₀, a₀) - A unit of length based on the radius of the first Bohr orbit of hydrogen 1.
• classical electron radius (6 facts) (r_e)
• gravitational radius (2 facts) - The radius which an object should have in order that light emitted from its surface just ceases to escape from its surface.
• Holmberg radius (2 facts) - The radius of an external galaxy at which the surface brightness is 26.6 mag arcsec^-2. This criterion was developed by Holmberg in 1958 to estimate the actual dimensions of the major and minor axes of a galaxy without regard to its orientation in space.
• Hubble radius (5 facts) (c/H) - The radius of the observable universe ().
• Larmor radius (2 facts) - The radius of the circular orbit that a charged particle describes transverse to a magnetic field.
• solar radius (3 facts) - A unit of length based on radius of Sun
• velocity-of-light radius (2 facts) - The radius of a rotating neutron star at which the rotational velocity of the plasma approaches the velocity of light. (also called velocity-of-light cylinder)