Charge densityIn electromagnetism, charge density is the amount of electric charge per unit length, surface area, or volume. Volume charge density (symbolized by the Greek letter ρ) is the quantity of charge per unit volume, measured in the SI system in coulombs per cubic meter (C⋅m−3), at any point in a volume. Surface charge density (σ) is the quantity of charge per unit area, measured in coulombs per square meter (C⋅m−2), at any point on a surface charge distribution on a two dimensional surface.
Halo 4Halo 4 is a 2012 first-person shooter video game developed by 343 Industries and published by Microsoft Studios for the Xbox 360 video game console. Halo 4s story follows a cybernetically enhanced human supersoldier, Master Chief, and his artificial intelligence construct Cortana, as they encounter unknown threats while exploring an ancient civilization's planet. The player assumes the role of Master Chief who battles against a new faction that splintered off from remnants of the Covenant, a former military alliance of alien races, and against mechanical warriors of the Forerunner empire known as the Prometheans.
MagnetarA magnetar is a type of neutron star with an extremely powerful magnetic field (~109 to 1011 T, ~1013 to 1015 G). The magnetic-field decay powers the emission of high-energy electromagnetic radiation, particularly X-rays and gamma rays. The existence of magnetars was proposed in 1992 by Robert Duncan and Christopher Thompson. Their proposal sought to explain the properties of transient sources of gamma rays, now known as soft gamma repeaters (SGRs).
