Salam (May God Bless You). Todays article is Practical Electricity. It will feature information about electrical components which we observe in our daily lives but sometimes just ignore it because we lack the knowledge of the importance of such components.
Direct and Alternate currents
In smaller circuits we use batteries and cells to provide with sufficient amount of energy, these sources of energy provide a direct current, d.c, which means it will not change its direction. If we observe the direct current in a p.d against time graph we can see that the d.c can be negative or positive but will not change its p.d. To represent the symbolic form of the d.c then we just draw a cell or battery to represent a direct current.
An alternate current, a.c, is a current which can change its direction. It is mainly provided by a mains supply. If a.c is observed in a p.d against time, then we can see that an a.c current changes its p.d over time, meaning it might be negative or positive in the next few seconds. To represent the alternate current we use the shown symbol.
Electrical Apliances using electric heating and electric lighting
Electricity is used in homes and offices for apliances which use the electricity to convert the electrical energy into other useful forms of energy. This is very useful as electricity is a clean energy and does not produce any waste. The electrical energy is converted mostly into heat energy, espacially in those appliances which use it for such purpose.
Such appliances have a special rod or a piece of wire which is an alloy of chromium and nickle, called a nichrome. Such rods have a very high melting point. The rod has a lot of resistance and therefore the electrical energy is conveted into heat energy. In appliances like a heater it is used as a rod but in appliances like a kettle it is used as wire insulated from the water in the kettle which helps heat it up.
An incandescent or filament bulb uses the electrical energy to convert it into light and heat energy. The bulb has a filament in it made of a metal called tungsten which also has a high resistance, about 3422°C. When a current passes through it, then the filament converts almost 10% of the energy into light energy while the rest is converted into heat energy which is why after a short time the bulb heats up. The bulb has an inert gas inside it which may be argon or nitrogen, we use these gases because the tungsten can react with oxygen and may cause an explosion.
An alternative to the incandescent bulb is the fluorescent bulb. The bulb has two electrodes in it and mercury vapour, the inside surface is coated with fluorescent powder. When the electrodes are powered, the mercury atoms become agitated and they release ultravoilet radiation. The ultravoilate radiaiton is absorbed by the fluorescent powder which causes it to glow.
Power is the rate at which energy is transformed into another form of energy. This is also known as work. Therefore for electrical devices we use the formula: P = IV, P is for power, I is for current and V is for voltage.
For energy we use the equation: E=IVt, E is for energy, I is for
Three pin Plug
The mains electricity is used up by connecting a plug with a socket. The most common type of plug used is the three pin one. It has three pins, two lower pins which are short and the top pin which is longer than the lower two becuase it is used to open the grates in the socket holes which connects to the lower two pins. This is a safety measure to prevent anything to be pushed into the socket.
First of all the plug has a plastic casing which serves as an insulation from the electricity which can be hazardous. The inside of the plug has cable clamp in it which grips the cable tightly enough to prevent it from falling out when pulled or tripped over. The plug has a fuse in it connected with a live wire. The plug also has a neutral wire and an earth wire which is connected to earth. The wires are color coded; neutral wire is blue colored, live wires are brown colored, and an earth wire is either yellow colored or brown colored.
The safety measures in a circuit is in several forms. The most common one is the presence of fuses in a circuit. Fuses contain small pieces of wire contained in a ceramix container, these wires can only carry a certain amount of current like 5 A, or 7A but whatever the limit, if the current exceeds the limit, the wire melts causing the circuit to be broken. This is useful as in an appliance there are many components which make up to a lot of resistance but sometimes wires get cross connected causing a new circuit being made which reduces the resistance of the circuit and therefore increases the current. This is very dangerous and can give the user a shock if he/she touches the appliance. To avoid this fuses are plugged in which break up the circuit in case of an increase in current.
An appliance also has an earth wire mainly in its plug. The earth wire is connected to the earth which causes the current to flow to the earth in case it rises above the limit. This is a good safety measure and can prevent you getting electric shocked. Another safety measure is that appliances may be covered with an insulator like plastic making it double insulated. Even if the inside circuit gains a boost of current it won’t affect the outside layer of the appliance, these kind of appliances do not need an earth wire.