Current electricity important points copy notes Class 12 Chapter 3 Physics

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Diagonal Relationship between Beryllium and Aluminium || Relation between Beryllium and Aluminium

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  Diagonal Relationship between Beryllium and Aluminium The ionic radius of Beryllium (Be 2+) is estimated to be nearly 31 pm; the charge/radius ratio Or e/m ratio is nearly the same as that of the Al 3+ ion. Hence beryllium resembles aluminium in these ways. Some of the similarities are given below: » Like Aluminium, Beryllium(be) is not readily attacked by acids H+ donor because of the formation of an oxide film on the surface of the metal by reacting with oxygen, i.e. they are rendered passive by nitric acid. » Beryllium hydroxide[[Be(OH)4]2] dissolves in excess of alkali to give a beryllate ion, [ Be(OH)4]2– just as aluminium hydroxide[Al(OH)3] gives aluminate ion, [Al(OH)4] » The chlorides of metals beryllium and aluminium have Cl– bridged chloride structure in vapour phase. Both the chlorides are soluble in organic solvents and are strong as Lewis acids They are used as Friedel Craft catalysts. » Beryllium(Be) and aluminium(Al) ions have strong tendency to form complexes, (Be...
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AC GENERATOR

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                                         AC GENERATOR  The Phenomenon of electromagnetic induction has been technologically exploited in many ways. An exceptionally important application is the generation of alternating currents (AC). ~ BASIC DESIGN  The basic elements of an ac generator are shown in Figure.  • It consists of a coil mounted on a rotor shaft.  • The axis of rotation of the coil is perpendicular to the direction of the magnetic field.  • The coil (called armature) is mechanically rotated in the uniform magnetic field by some external means.  • The rotation of the coil causes the magnetic flux through it to change, so an emf is induced in the coil.  • The ends of the coil are connected to an external circuit by means of slip rings and brushes.   PRINCIPLE  One method to induce an emf or current in a loop is through a change i...
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MECHANICAL PROPERTIES OF SOLIDS

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             1. Introduction   The motion of a body depends on how mass is   distributed within the body. We restricted ourselves to simpler situations of rigid bodies. A rigid body generally means a hard solid object having a definite shape and size. But in reality, bodies can be stretched, compressed and bent. Even the appreciably rigid steel bar can be deformed when a sufficiently large external force is applied on it. This means that solid bodies are not perfectly rigid.A solid has definite shape and size. In order to change (or deform) the shape or size of a body, a force is required. If   you stretch a helical spring by gently pulling its ends, the length of the spring increases slightly. When you leave the ends of the spring, it regains its original size and shape.  The property of a body, by virtue of which it tends to regain its   original size and shape when the applied force is removed, is known as elasti...
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EQUILIBRIUM

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                   1. Introduction Chemical equilibria are important in numerous biological and environmental processes. For example, equilibria involving O2 molecules and the protein hemoglobin play a crucial role in the transport and delivery of O2 from our lungs to our muscles. Similar equilibria involving CO  molecules and hemoglobin account for the toxicity of CO. When a liquid evaporates in a closed container, molecules with relatively higher kinetic energy escape the liquid surface into the vapour phase and number of liquid  molecules from the vapour phase strike the liquid surface and are retained in the liquid phase. It gives rise to a constant vapour pressure because of an equilibrium in which the number of molecules leaving the liquid equals the number returning to liquid from the vapour. We say that the system has reached equilibrium state at this stage. However, this is not static equilibrium and there is a lot ...
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10th NCERT physics all SI units

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 Mass  → kilogram (kg)  Time → second (sec)  Speed → m/s Velocity → m/s Temperature → kelvin (K)  Amount of substance → mole(mol)  Length → meter (m)  Current (I) → Amphere (A)  Potential difference → volt (V)  Weight → kilogram (kg)  Luminous intensity → Candella (Cd) 
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