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ELECTRICAL MEASURING INSTRUMENTS For the detection or measurement of electric current, potential difference, and resistance certain instruments have been devised viz. The galvanometer for the detection of small currents measurements of small currents of the order of micro amperes or mili amperes the voltmeter or potentiometer for the measurement of potential difference (and voltage) between two points of a circuit are the EMF of a source the ammeter for the measurement of large currents the wheatstone bridge the meter Bridge the post office box and the ohmmeter for the measurement of resistance. THE MOVING COIL GALVANOMETER The moving coil galvanometer is a basic electrical instrument it is used for the detection (and Measurement) of small currents. Its underlying principle is the fact that when a current flows in a rectangular coil placed in a magnetic field it experiences a magnetic torque. If it is free to rotate under a controlling torque, it rotates through an angle proportional t...
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TYPES OF ELEMENTS BASED ON ELECTRONIC CONFIGURATION

The periodic table has been divided into s,p,d and f blocks on the basis of electronic configuration :

(1) The Noble Gases :

In the periodic table, the  noble gases are found at the end of each period in zero group.They are colorless gases up to some extent chemically non reactive and diamagnetic.

The electronic arrangement of ns2,np6 is exceptionally stable.Discontinuities in energy level diagram occur after these configurations are attained.With the exception of helium (Z=2) all the noble gases have outer electronic configuration of 2s2,2p6 no atom has a complete outer shell with exception of helium and noble gases.

(2) Representative elements of typical elements :

All elements of sub-groups of the periodic table are representative of typical elements.They include metals ,non metals and metalloids.Some of the elements are paramagnetic and some are diamagnetic.These include of elements of s and p-blocks.

(a) s-block elements :

In these elements the last electron enters ns orbital which is being progressively filled.The elements of I A and II A belong to S Block.The valence shell configuration varies from ns1 and ns2 where n in the period in which the element is present.

(b) p-block elements :

The elements in which the elements is present being progressively filled are called p block elements.The elements of the groups III A,IV A,V A ,VI A ,VII A and zero group are members of p-blocks.The valence shell configuration of these elements ranges from ns2,np1 to ns2 and 2ps.

(3) d-block elements (outer transition elements) :

The elements in which the last electron enters (n-1)d orbitals are called d-block elements.These elements are called outer transition elements. The valence shell configuration of these element ranges from ns2,(n-1)d1 to ns2 ,(n-1)d10,There are four series of outer transition elements,the 4th is incomplete.

(4)  f-block elements (Inner Transition Elements) :

The elements in which the last electron enters (n-2)f orbital are called f block elements or inner transition elements.They have outer electronic configuration : ns2,(n-1)d1,(n-2)f 1-14
 

 

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