Alternating current class 12 key concepts || A C class 12 key concepts || Alternating current formulas class 12 ||

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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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PHYSICAL WORLD

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                      1. Introduction In this we will learn the full topic about physical world. To know about " What is physics " And about " Scopes of physics " Click on the above link. The word Science originates from the Latin word S c i e n t i a meaning ‘to know’ , ‘knowledge’. Science, in a broad sense, is as old as human species. The early civilisations of Egypt, India, China, Greece, Mesopotamia and many others made vital contributions to its progress. From the sixteenth century onwards, great strides were made in science in Europe. The interplay of theory and observation (or experiment) is basic to the progress of science. Science is ever dynamic. There is no ‘final’ theory in science and no unquestioned authority among scientists. As observations improve in detail and precision or experiments yield new results, theories must account for them, by introducing modifications.  The modifications may not be drastic and...
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Computer science MCQ questions Class 12 Python

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 SECTION-A 1. When reading a file line by line, the exact contents can be printed by: (A) Using readline ( ) (B) Using readlines ( ) (C) Using ‘,’ after every print statement (D) Both (A) & (B) 2. Choose the correct Python expression for the following mathematical expressions p+q/(r+s)4 (A) p+q / math.pow ((r+s), 4) (B) p+q/(r+s)^4 (C) p+q / math.pow (r+s,4) (D) (p+q) / math.pow (r+s) 3. Identify the correct statement for opening text file data.txt in total folder of c:drive in read mode. (A) F = open (“c:\\total\\data.txt”, “r”) (B) F = open (“c:\total\data.txt”, r) (C) F = open (“c:\total\data.txt”) (D) F = open (“\total\data.txt”, “r”) 4. A valid combination of atoms and operators forms a Python (A) Statement (B) Expression (C) Condition (D) None of these. 5. The default file open mode in Python is (A) Write (B) Read (C) Append (D) Read/write 6. In Python, a block is executed in an .................... (A) Function (B) Module (C) Py file (D) Execution frame 7. Consider ...
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Distinction between Electromagnetic Waves and Matter Waves

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  Difference   between Electromagnetic Waves and Matter Waves » Electromagnetic waves 1. Electromagnetic waves are associated with electric and magnetic fields perpendicular to each other and to the direction of propagation of radiation. 2. Electromagnetic waves can be radiated into space or emitted. 3. They do not require any medium for propagation i.e., these waves can pass through vacuum. 4. All electromagnetic waves travel with the same velocity.  5. The velocity of all electromagnetic waves is equal to that of light (3 x 108 m/s). 6. The wavelengths of electromagnetic radiation are much large .   » Matter waves 1. Matter waves may not be associated with electric and magnetic fields. 2. Matter waves are neither radiated into space nor emitted by the particles. These are simply associated with the particles 3. They require medium for propagation i.e., these waves cannot pass through vacuum. 4. Matter waves travel with different vel...
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