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...
CHLORINE ELECTROLYSIS METHOD: Chlorine is manufactured by the electrolysis of aqueous solutions of sodium chloride.For this purpose two cells are used which are described below: (a) NELSON'S CELL: This cell consists of U-shaped perforated steel vessel which acts as cathode and carbon rod as anode.This U-tube is separated from anode by asbestos layer on the inner wall of the U-Tube as shown in figure The U-tube is filled by aqueous solution of sodium chloride.On passing the electric current,chlorine is obtained at anode reaction: (i) Ionization NaCl ---------> Na + Cl (ii) Reaction at anode 2Cl - 2e ----------> Cl2 (b) CASTNER-KELLNER'S CELL: This cell has a Cathode consisting of layer of mercury at the bottom of cell which flows from right to left.Saturated solution of sodium chloride also flows slowly through the cell in same direction as the mercury.The anode rods are of graphite which dip into the solution of sodium chloride. On electrolysis chlorine is liberated at ...