Physics - Mock Test 13

Graphite has a tendency to behave very much like a metal because the carbon molecules arrange themselves into a lattice structure. The crystal lattice is the same orientation that metal forms, and it allows the free-movement of electrons, making it a good electrical conductor. The characteristics possesses by the graphite for conduction is far better than the dry air paper and kerosene and that's what makes it a good conductor.

Sudden and great fluctuations of the barometer at any time of the year indicate unsettled weather for several days, perhaps a fortnight. If the barometer falls two or threetenths of an inch in four hours, one can expect a gale of wind. If the surface of the mercury in the cistern of the barometer vibrates upon the approach of a storm, the gale can be expected to be severe.

The central mass of the sun becomes increasingly hot and dense. eventually initiating thermonuclear fusion in its core. It is thought that almost all other stars form by this process. nuclear fusion is a nuclear reaction in which two or more atomic nuclei join together, or "fuse", to form a single heavier nucleus. During this process, matter is not conserved because some of the mass of the fusing nuclei is converted to energy which is released.

For fixed (point-to-point) services, communications satellites provide a microwave radio relay technology complementary to that of communication cables. They are also used for mobile applications such as communications to ships, vehicles, planes and hand-held terminals, and for TV and radio broadcasting. Microwave technology is extensively used for point-to-point telecommunications (i.e., non broadcast uses).

The heat content of anthracite ranges from 22 to 28 million Btu per short ton (26 to 33 MJ/kg) on a moist, mineral-matter-free basis. Anthracite ("coal-like") is a hard, compact variety of mineral coal that has a high luster. It has the highest carbon content, the fewest impurities, and the highest calorific content of all types of coals, which also include bituminous coal and lignite.

The energy possessed by a body by virtue of its motion is called kinetic energy. Potential Energy is the energy possessed by virtue of its position or configuration. When a body falls from an aeroplane, there is increase in its acceleration.

The specific heat of water is higher than all other common substances. Hence, water is used for heating purposes (as in hot water bottles) and for cooling purposes (as in radiators of cars). Off all the liquids, mercury has the lowest specific heat due to which it is used as a thermometric liquid.

Minimum number of unequal vectors which can give three zero resultants.

When a body is placed in water, the upthrust or buoyant force acting on it depends upon the following factors: (1) Volume of the body submerged in the liquid - (V), or volume of the liquid displaced - (V); (ft) Density of the liquid - (d); and (Hi) Acceleration due to gravity In-line.

A fuse places a limit on the amount of current that can be drawn by an electric circuit by opening (blowing or melting) when the current exceeds a preset limit. This protects the circuit and the surroundings from fire or damage in the case of an overload or short circuit.