Arc WeldingA welding process in which an electric arc is used to produce heat to melt and join the metals is known as arc welding. In the arc welding, an AC or DC welding power supply is used to create the electric arc between a consumable or non-consumable electrode and the base material.Laser WeldingThe welding process in which a laser beam is used as the source of energy to melt the materials being joined is known as laser welding. It is a high energy density beam process, and can be used to join thick materials with deep and narrow weld.Hybrid ... Read More

A low-pressure mercury vapor gas discharge lamp that uses fluorescence effect to produce visible light is known as fluorescent lamp or fluorescent tube.There are some common faults in case of the fluorescent lamps. These faults, their reasons and treatment methods are described in the following table −Type of FaultReasons of FaultTreatment or Repairing MethodsThe fluorescent lamp does not start.Loose and defective holders.Defective fluorescent tube.Defective starter switch.Defective choke.Turn the tube through 90° and check the connections and holders.Replace the tube.Try another starter switch / replace the starter switch.Replace the choke.Fluorescent lamp blinking ON and OFFLoose contacts.Wrong circuit connections.Low supply voltageDefective starter.Defective ... Read More

What is Electrolysis?The process in which ionic substances are decomposed into simple substances by passing an electric current through them is known as electrolysis.In other words, the process based on the fact that electrical energy can produce chemical changes is known as electrolysis.Applications of ElectrolysisNowadays the electrolytic process is widely used in various industrial applications. The major applications of the electrolysis are given below.Extraction of Metal from their OresThe electrolytic process is used for extracting out the pure metal from their ores, this process is known as electro-extraction. In the electro-extraction, the metal ore is treated with strong acid or ... Read More

Light is the natural agent that simulates sight and makes the things visible. Light is also known as visible electromagnetic radiation as it is capable of causing a visual sensation and its wavelength varies from 380 nanometers to 780 nanometers.Characteristics of LightThe main characteristics of light are given as follows −Light is nothing but a form of energy produced by a luminous object.It is an electromagnetic radiation, thus it can travel through vacuum.In an optically homogeneous medium, light travels in a straight line.When light falls on a polished surface such as mirror or metal surface, it bounces back. This bouncing ... Read More

What is Submerged Arc Welding?Submerged arc welding (SAW) is a welding process that involves the formation of an electric arc between a continuously fed electrode and the workpiece to be welded. The process of submerged arc welding was developed by the Linde-Union Carbide Company.SAW requires a continuous fed of consumable solid or flux cored tubular electrode. In case of submerged arc welding, the molten weld and the arc are protected from the atmospheric contamination by being submerged under a blanket of granular fusible flux consisting of lime, silica, manganese oxide, calcium fluoride and other compounds.A simplified schematic diagram of submerged ... Read More

What is Resistance Heating?When the heat is produced by passing electric current through the resistance of a conductor, it is called electric resistance heating (ERH). This method of electric heating is based on the principle of I2R loss. If ‘P’ is the electric power developed in the heating circuit and ‘t’ is the time in seconds. Then, heat energy produced is given by, H = 0.24 pt CaloriesThe power P depends upon the magnitude of current through the circuit. The source of electric supply can be AC or DC of any suitable voltage and frequency.The major applications of the resistance ... Read More

What is Plasma Arc Welding?Plasma arc welding (PAW) is a welding process in which the electric arc is formed between an electrode and the workpiece. The electrode used in the plasma arc welding is usually but not always made of sintered tungsten. The process of plasma arc welding was discovered by Robert Merrell Gage in 1957.By positioning the electrode within the body of the welding torch, the plasma arc can be separated from the shielding gas envelope. Then, the plasma is forced through a fine-bore copper nozzle which constricts the arc and the plasma exits the nozzle orifice at high ... Read More

The type of electric welding in which an arc is established between the workpiece and the filler metal electrode is known as metallic arc welding or simply metal arc welding.The figure shows the simplified circuit diagram of metallic arc welding.In metallic arc welding, the intense heat of the arc forms a molten pool in the metal being welded and at the same time melts the tip of the electrode. As the electric arc is maintained, filler metal from the tip of the electrode is transferred across the arc and it fuses with the molten base metal.The electric arc in this ... Read More

Induction heating is the process of heating the materials which are electrically conductive by electromagnetic induction like metals.Working Principle of Induction HeatingInduction heating makes use of the induced current by the electromagnetic induction in the charge to be heated. The induction heating works on the principle of transformer action, in which the primary winding which is supplied from an AC source is magnetically coupled to the charge, to be heated, which acts as a short-circuited secondary of a single turn.When the AC supply is connected to the primary winding, it induces currents in the charge. As the secondary, i.e., the ... Read More

What is Gas Tungsten Arc Welding?Gas tungsten arc welding (GTAW) is an electric arc welding process which uses a non-consumable tungsten electrode to produce the weld. The gas tungsten arc welding is also known as tungsten inert gas (TIG) welding.In case of GTAW, the weld area is protected from the atmospheric contamination by a shielding gas. This shielding gas usually an inert gas such as argon. In general, a filler material is also used, although some welds, known as autogenous welds, do not require it.In this welding process, a constant current welding power supply is used to produce energy which ... Read More