Knowledge Pays Off

Why are the kilogram weights hexagonal?
Kilogram weights are hexagonal for stability, as volume is the surface area multiplied by height. For a hexagonal object, the surface area is maximum as compared to other angular shapes, plus the height is fixed for every weight. The higher the surface area, the better the stability.
What is super string theory?
It is a model of fundamental physics whose building blocks are one-dimensional extended objects called strings, rather than the zero-dimensional point particles which form the basis for the standard model of particle physics. By replacing point-like particles with string, an apparently consistent quantum theory of gravity emerges. Moreover, it may be possible to unify the known natural forces (gravitational. electromagnetic, weak nuclear and strong nuclear forces) by describing them with the same set of equations as described called the grand Unified Theory (GUT).
What particles are emitted when gamma rays strike a metallic plate? What is the phenomenon called?
Gamma rays, like light rays, are basically electromagnetic rays. When gamma rays of optimum frequency strike a metal plate – they emit electrons (negatively charged particles). This phenomenon is called the photoelectric effect.
What are Polar Coordinates?
It is a system of coordinates in geometry whereby the position of a point, say P, in a plan can be determined with reference to a fixed point called origin, denoted by O, and a predetermined direction represented by a ray OA. The measure of length OP, denoted by r, and the measure of the angle that OP makes with OA, generally denoted by a Greek letter theta, are called polar coordinates of P and, P is called the graph of r and theta. One pair of values of r and theta corresponds to only one point in the plane and one point in the plane corresponds to only one pair of the values of r and theta.
How is a satellite phone different from a cellular phone?
Satellite and cellular phone are wireless devices. They almost look alike but the way they work is totally different. A cellular phone functions on the basis of cells, and hence are called cell phones. The whole network area is divided into small areas and an antenna is installed in each area. These are also called towers. When a cellular phone is moving, it enters from one cell to another. When it crosses the border of one cell, the phone sends a signal to the MTSO (Mobile Telephone Switching Office). With the help of Control channel the data base of the MTSO relocates the phone in a new call or area. Satellite phones use low earth orbiting (LEO) satellites. When a satellite phone is turn on, a signal goes up to any number of satellites of a group the phone is registered with. When a person make from his handset, a signal goes to nearest orbiting satellite. The satellite connects to the gateway or ground station. Than the gateway takes the call to the destination.
What does Probiotic mean?
Probiotic is a microbe that protects its host and prevents disease. The best known probiotic is Lactobacillus acidophilus, found in yogurt, acidophilus milk, and supplements. Probiotics counter the destruction of helpful intestinal bacteria by antibiotics. They are useful in preventing antibiotic-as-sociated diarrhoea. The yeast SBoularduu and three strains of Lac- tobacillus are also useful.
What is a crystal radio?
A crystal radio is the basic form of a radio, which can detect radio signals without a power supply. It has very few parts and it can be built in a short time with commonly available items. It works best if there is a transmitter within 40 km of the set. Simple crystal radios are often made with a few handmade parts like an antenna wire, tuning coil of copper wire, crystal detector and ear phones. A crystal radio receive programmes broadcast from radio stations which convert sound into radio waves and send out the signals everywhere. The crystal radio antenna, a very long wire, picks up the signals and passes them through the set as an electronic current. It uses a crystal detector to convert this radio wave electricity to sound electricity. The detector can be made from a special rock of galena in a holder. It uses earphones to convert the sound electricity to the sound you can hear.

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