The heating effect of electric current is widely used in our day-to-day life. The electric iron, kettle, toaster, heater etc. are used as alternatives to the conventional methods of cooking and laundry. The same is used in electric bulbs which is the alternative of conventional lamps. These devices have revolutionized the world over the years. In this section we will discuss the concept of heating effect of electric current and its applications.
When an electric current is passed through a conductor, it generates heat due to the hindrance caused by the conductor to the flowing current. The work done in overcoming the hindrance to the current generates heat in that conductor.
Following are the devices in which heating effect of current is harnessed for other purposes:
Mica is an insulator that is placed between the metal part and the coil in an iron. The coil becomes heated with the passage of current which is then transferred to the metallic part through mica. Finally, the metal part becomes heated which is then used for ironing clothes.
Electric bulb contains a thick metallic wire made up of tungsten metal. The metal is kept in an inert environment with a neutral gas or vacuum. When current flows through the tungsten wire, it becomes heated and emits light. Most of the electric power drawn in the circuit from the electrical source is dissipated in the form of heat and the rest is emitted in the form of light energy.
In an electric heater, high resistance nichrome wire is used as a coil. The coil is wound on grooves made up in ceramic material or china clay. When the current flows in the coil, it becomes heated, which is then used to heat cooking vessels.
In any electrical instrument, due to sudden rise of current, the instrument gets burnt down which sometimes results in fire. A conducting wire with low melting point is connected in series with the circuit to avoid this type of accident. When the current rises, the wire melts due to excessive heating, thus breaking the electrical circuit.
For harnessing the heating effect of electric current, the element of appliances is required to have high melting points to retain more heat.
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