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Electric - Its chemical effect | Electric - Its Heating Effect

Electric - its chemical effect  We have studied the production of electricity through chemicals in voltaic and other types of cells.  In tho...

Electric - Its chemical effect | Electric - Its Heating Effect

Electric - its chemical effect 

We have studied the production of electricity through chemicals in voltaic and other types of cells.  In those cells, chemical reactions take place in the electrolytes and cause flow of charges in the external circuit.  Similar, electricity flowing through an electrolyte (electrical conductor in liquid form) taken in a container can cause chemical reactions in the electrolytes.  This is known as chemical effect of electricity.  The most commonly occurring chemical reaction in an electrolyte, when an electric current passes through it is the chemical decomposition reaction '.  Chemical decomposition is the process of splitting of a compound into its constituent ions or elements.  The process of producing chemical decomposition of a compound by passing electricity through the compound is known as “electrolysis” and the solution through which electricity passes is called electrolyte.




Electric - Its Heating Effect 

If an electrical conductor like a nichrome wire is connected to the terminals of a battery, we observe that, after some time, heat is produced through the wire. Thus, the energy is transformed from electrical form into heat form. This is known as the heating effect of electric. When a solid electrical conductor like a metallic wire is connected to the terminals of a battery, electric current, i.e., flow of charge, takes place through the conductor by way of the motion of free electrons present in it from one end to the other end. While the free electrons of the wire are in motion through it, they collide with atoms or molecules of the substance giving rise to restriction to their free flow. This restriction to the flow of charges in a conductor is known as its 'resistance' or more precisely 'electrical resistance'. Due to the collision of free electrons in the conductor with its atoms or molecules, their kinetic energy increases and this increase in the kinetic energy is exhibited in the form of heat. Thus, we can say the more the electrical resistance of a conductor, the more is the heat produced. It is found that the resistance of a conductor is directly proportional to its length and inversely proportional to its area of cross seetion. 

If T and 'a' are respectively the length and the area of cross section of a conductor whose resistance is 'R', then mathematically, R l and R - Thus, Rx a The heating effect of electric current has a wide variety of applications. Some of them are discussed below.




1. An Electric Bulb: It was invented by Thomas Alva Edison. It is a glass bulb, spherical at the bottom portion and extended to cylindrical shape at the top. It contains an inert gas like argon or helium at low pressures. Inside the glass bulb, a tiny conducting coiled coil of tungsten wire having high resistance is fitted and is called filament of the bulh The filament rests on two tiny wires called supporters and its ends are connected to leads through which electric current passes. The leads and filament supporters are fixed to a glass support, as shown in Fig. 8.18 and the upper portion is sealed with glass. Above the seal, an aluminium cap is attached and the leads are connected to the top of the cap as two terminals. On the lateral sides of the aluminium cap, two small projections are provided diametrically opposite to each other to help in fixing the bulb to its holder. As the resistance of the filament is much higher, it gets red hot and then emits. light when electricity is passed through it.  

2. An Electric Stove: An electric stove consists of a porcelain base fixed in a casing and a filament fixed in the groove of the base. The filament is a long thin coiled wire and has high resistance. The ends of the thin filament is connected to the terminals by means of leads. When electric current passes through the filament, it gets red hot and generates heat, which can be used for cooking.  

3. An Electric Iron: An electric iron contains a heating element, usually made of nichrome (an alloy of nic kel and chromium) placed between two mica sheets. These sheets are placed on an iron base, Above the mica sheets in which heating element IS placed, an asbestos sheet is placed and above that a dome is placed and fixed to the iron base. The ends of the heating element are connected to the mains through connecting wires. The mica sheets placed on either side of the heating element do not conduct electricity but transfer the heat. Thus, the iron base is heated and transfers the heat to the clothes being pressed. The asbestos sheet, placed above the mica sheet being a bad conductor of heat, does not allow the heat to move in the upward direction. A handle preferably made of ebonite is attached to the dome.


4. A Soldering Gun or Soldering Iron : We need to connect so many wires at so many places in a complex electric circuit . The connections are perfect when the joints of the wires are perfect . To have a perfect joint , the ends of the wires have to be joined in a molten state or a fused state . When the wires are made of less fusible material , in order to make the joint a perfect one , we use another fusible material , which is an alloy , to join the edges of the less fusible materials . This fusible alloy is called solder and the process of joining the wires with a solder is called soldering . For this purpose a metallic rod is used ; which is called soldering gun or soldering iron . One end of the rod is pointed and wedge - shaped and the other end is fixed to a hollow metallic tube . A heating element is placed inside the hollow tube and is in contact with the rod , as shown in the figure . To the other end of the rod , a handle preferably made of bakelite material is attached . The heating element in the soldering iron is connected to the mains by means of a connecting wire through the handle  

5. Electric Immersion Heater : The heating element in an electrical immersion heater is usually made of nichrome ( an alloy of nickel and chromium ) wire wound in the form of a spring . The heating element is placed in a hollow brass tube . The space between the brass tube and the heating element is filled with magnesium oxide or quartz sand . This avoids the contact of the heating clement to the brass tube and avoids electric shock to the person handling it . The magnesium oxide or the quartz sand used in the heater is an electric insulator but is a good conductor of heat The ends of the beating element are connected to brass terminals fixed in a casing made of bakelite and the terminals are connected to the mains through a plus and wire . Nichrome has high electrical resistance and so it is the most preferred material for the preparation of heating elements. Electric Fuse : Electric frase is the device used in the household electric wiring that protects appliances from high current . Fuxe wire is connected berween the mains and leads of the primary circuit of an electric appliance . When excess amount of electricity passes through the wire , the fuse wire gets heated and the heat produced fuses or melts the wire breaking the power supply to the circuit of the appliance . Thus , the electric appliance is protected from the passage of high electric current which destroy the appliance.