Heating Effect of Electric Current
When an electric current flows through a wire, the wire gets hot. This is known as the heating effect of electric current. The factors that affect the production of heat in a wire through which an electric current flows are the length and thickness of the wire, the duration of flow of current, and the material of the wire.
Some appliances that work on the property of the heating effect of electric current are electric room heater, electric roti maker, electric iron, toaster, hair dryer, electric stove, immersion water heater, food warmer, electric coffee maker, electric rice cooker and geyser. These appliances have coils of wire known as heating elements which produce heat. As current flows through these electrical appliances, the heating elements turn bright orange red in colour. This is because a huge amount of heat is produced. Different appliances have different types of heating elements. The type of heating element depends on the function of the appliance. Some appliances are required to produce more heat than others.
The electric fuse works on the principle of the heating effect of electric current. An electric fuse is a safety device to prevent damage to an electrical circuit when excessive current flows through it. It is made of a special material. As the current increases beyond a limit, the wire in the electric fuse melts and breaks off. The fuse is then said to have blown off. The circuit is broken and current stops flowing through it. Thus a fuse prevents fires. There are various types of fuses. Some fuses are used only in buildings, while others are used in appliances.
Reasons for Excessive Current
When all the appliances are connected to the same socket, they draw more current, and so the load increases. When the insulation on the wires is torn, two wires carrying current may touch each other directly. This causes a spark, which leads to fire. This is termed as a short circuit. If a fuse is not used, overloading and short circuits occur which results in fire.
Compact Fluorescent Lamp (CFL)
We use electric bulbs to obtain light. Due to the heating effect, a part of the energy received by the bulb is used up, and hence some energy is wasted. CFL’s do not depend on the heating effect of electricity to produce light, since they do not use filaments. Using CFL’s instead of ordinary bulbs minimises wastage of electricity. In CFL’s, light is generated using two electrodes. The fluorescent coating inside each tube makes the light brighter.
We should purchase only appliances that bear an ISI mark. ISI stands for Indian Standards Institute. If an appliance bears the ISI mark, it means that it is safe and will not waste electrical energy. Moreover, it is a mark of quality.
Miniature Circuit Breakers (MCBs)
Instead of fuses, MCBs are used nowadays. MCBs are switches that turn off automatically when there is an overload or a short circuit. After solving the problem in the circuit, the switch can be turned back on, and then the current flows as usual.