Electricity in our Lives
No single discovery has influenced our lives and existence more than electricity. We observe a huge usage of electricity in our daily life. Electricity is everywhere. It lights our homes, cooks food, runs our mobile gadgets, and plays shows on TV for us. Electricity provides air-conditioning for us to live and work in a suitable environment. It provides massive assistance in medical and medicine field, saving thousands of life and making our life more livable and better. It would not be possible to communicate with each other from such long distances without electricity. People now can read books and online articles on a computer sitting at home instead of physically going to libraries. Electricity has made our daily routine more efficient and productive.
Basic Principles of Electricity
Electricity is basically a flow of electrons in a circuit in the presence of some potential difference across a circuit. Electricity reaches our homes in the United States generally with three wires. One wire of either black or red color is called live or hot wire, while the other wire of either white or grey color is called neutral wire. Finally, there is a green or bare wire called the ground wire. The live, or hot, wire has a certain potential with respect to neutral wire and it provides electric current to all appliances, while the neutral wire collects all current back to grid. There is another wire in our home circuitry called ground wire which helps protect us from electric shock.
Faraday’s Law
Electricity is produced on the Faraday’s Law of electromagnetic induction. This principle says that if a closed circuit loop/coil moves back and forth, or rotates in a magnetic field, then electricity is generated in that circuit. Electric generators use this principle to produce electricity.
Current, Voltage, and Resistance
Electricity is mainly characterized by three basic electrical quantities which are current, voltage and resistance. The current is composed of the flow of electrons through a particular point in the circuit. It is defined as: “the number of electrons passing through any particular cross section of wire in one second”. It is measured in amperes (A) and is represented by following formula:
I=dQ/dt
Where Q is electrons, and t is time.
The voltage, or potential difference, is basically the driving force if electrons in a closed circuit. Voltage is measured in volts. It is usually denoted by V and represented by following formula:
V=dW/dQ
Where W is work done, and Q represents the charge in coulombs
The third electrical quantity is resistance (R) which is defined as: “the measure of opposition to the flow of current in a circuit”. It basically limits the current flow in a circuit. It is measured in ohms (Ω). Resistance of a material is related to its physical properties. Based on the resistance, there are three types of material, which are:
- Conductors which pass electric current easily
- Semi-conductors which allow to flow current under certain conditions
- Insulators which do not allow current to flow through them
You can visualize how an electric circuit works based on a filled water tank with a hole at the bottom of it. The water represents the amount of current which is coming out that hole. This water flow is limited by the dimensions of the hole which represents resistance. While the speed of water coming out depends upon height of water level which represents the voltage level.
The current, voltage and resistance are related to each other by Ohm’s law. This law states: “the electric current in a circuit is directly proportional to the applied voltage” and is represented by following equation:
V=I*R
Where V is voltage, I is current and R is resistance.
Direct Current and Alternating Current
There are two types of current or electricity. One is AC which is Alternating Current and other is DC which is Direct Current. Alternating current is defined as: “the current which changes its magnitude and direction with respect to time in a circuit” while direct current is defined as “the current whose magnitude and direction remains constant with respect to time”. Electric generators produce AC current based on Faraday’s electromagnetic induction principle, while batteries or cells produce DC current based on chemical reactions inside them.
The electricity that utility companies provide to their consumers is generally AC. Electricity has voltage level of 120V and frequency 60Hz in United States, while it is normally 220V and 50Hz in most European countries. However industries and factories may utilize three phases AC electricity because of their heavy loads.
Watts
Power, measured in watts, comes from multiplying the voltage times the current in a circuit. For example, a ceiling fan has load of around 100W, while iron has around 1000W as well. The electric energy for billing is measured in kilowatt hour (kWh) units. Kilowatt hours are recorded by the electric energy meters installed outside most homes and businesses. Kilowatt hours (kWh) are equal to the number of watts an appliance is rated for times the number of hours of usage for that appliance. If a 1000W load runs for 1 hour, it will be equal to 1kWh. The electricity bill of a consumer is calculated based on the number of kilowatt hours a customer uses in a month.