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...
REFINING OF PETROLEUM Petroleum is refined by distillation.Crude oil is carried by pipes to a fractionating column and heated to above 400 C.A number of products are obtained at different temperatures and condensed. More than 500 compounds have been formed in petroleum distillate boiling below 200 C.Gasoline or petrol is a mixture of hecane (C6H14) and heptane (C7H16) and Heptane (C7H16) Since the demand of gasoline is increasing due to to its increased use a fuel for automobiles, airplanes etc.The cracking is employed to obtain increased quantities of petrol from crude oil. REFORMING OF PETROLEUM :- Knocking is a sharp metallic sound produced in the internal combustion engine.Its a cause is gasoline of low octane number.T he octane number of gasoline is improved by reforming,a process some what similar to cracking,which again brings about the arrangements of straight chain alkanes into branched chain alkanes.If the petrol used is of such quality that its vapour mixed with air can...