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Black hole

A black hole is a place in space where gravity pulls so much that even light can not get out. The gravity is so strong because matter has been squeezed into a tiny space. This can happen when a star is dying. Because no light can get out, people can't see black holes. They are invisible. Space telescopes with special tools can help find black holes. The special tools can see how stars that are very close to black holes act differently than other stars. How Big Are Black Holes? Blacbe big or small. Scientists think the smallest black holes are as small as just one atom.These black holes are very tiny but have the mass of a large mountain. Mass is the amount of matter, or "stuff," in an object. Another kind of black hole is called "stellar." Its mass can be up to 20 times more than the mass of the sun. There may be many, many stellar mass black holes in Earth's galaxy. Earth's galaxy is called the Milky Way. The largest black holes are called "superma...
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Super Magnet

 The neodymium compound, Nd2Fe14B was first discovered in 1982 by General Motors and Sumitomo Special Metals. Since they were first introduced, stronger grades of neodymium magnets have become commercially available as manufacturing techniques have become more advanced. The strongest grade currently available is the N55, although it is not yet widely used. More common are N42 and N52 grades; a 50mm x 50mm x 25mm N52 neodymium block  style="background-color: white; color: #676767; letter-spacing: 0.6664px;">is capable of supporting a steel weight of 116kg vertically when in flush contact with a mild steel surface of equal thickness and produces a Gauss rating, the unit measurement of flux density, of 5,500 over 7,800 times stronger than that produced by the Earth at its magnetic poles. Electromagnets which harness electric currents to produce magnetic fields can be many times stronger than permanent magnets, however, they need a significant electrical current to produce their magnetic field.
Neodymium magnets are so strong because of their high resistance to demagnetisation (coercivity) and their high levels of magnetic saturation allowing them to generate large magnetic fields. A magnet's strength is represented by its maximum energy product value (BHmax) which is measured in Mega Gauss Oersteds (MGOe). Maximum energy product is a product of remanence (Br) and coercivity (Hc) and represents the area under the graph of the second quadrant hysteresis loop.

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