We do many works in our daily life. We do many of them through our physical activities. Some work is done with tools and other devices. But they also require energy. There are many types of energy like electrical energy, mechanical energy, thermal energy, light energy, and wind energy. In our daily life, we get electrical energy from the battery. Electricity is also produced from nuclear power plants, hydroelectric plants, wind farms, and sunlight. Eels produce electricity. They use this energy to protect themselves from their enemies. Fans, lights, televisions, washing machines, and refrigerators all require electricity to operate. Sources that generate electricity are called power sources.
Fig 1. Eels fish
The movement of electrons in an object causes a force. This energy is called electrical energy. The energy to do work is produced by the circulation of electric current in an electric circuit. This energy is called electrical energy. Electrical energy is converted into many energy forms. For example, electrodes, amplifiers, electromagnets, light bulbs, and chemical changes. Electrical energy is stored in batteries and capacitors. We use electrical energy to run various devices and chemical energy to cook food or run vehicles. Everything is available from one source. We need to know how to choose the source of energy required to obtain energy in usable form. An energy source must be more work can be done per unit mass, easily available, easy to store, and move and most importantly it is affordable. Electric energy sources are given below.
Large amounts of fossil fuels are burned every day in thermal power plants to produce electricity and heat water. It is called a thermal power plant as electrical energy is generated here using thermal energy. It is much easier to transmit electrical energy than to transport coal or petroleum over long distances. So, thermal power plants are installed near coal or oil fields.
The potential energy of falling water is converted into electrical energy in hydroelectric power stations. Although there are few waterfalls as a usable source of energy, hydroelectric power stations are coupled with dams.
The sun archives high temperatures by concentrating its rays to cook. Solar cells are covered with glass plates. This is achieved by using solar cells that convert solar energy into electrical energy. The main advantage of solar cells is that they have no moving parts and require little maintenance. A large number of solar cells are connected in a structure called a solar panel to provide electricity for practical use.
Wave energy is harnessed by constructing a dam with a narrow opening on the beach. A turbine installed at the dam’s opening converts the tidal energy into electrical energy. Kinetic energy can be obtained in the same way from offshore wind that produces electrical energy. Waves are created by strong winds blowing across the ocean. Only where the waves are strongest is the wave energy at a different rate. Various types of devices have been developed and used to harvest wave energy for turbine rotation and power generation.
Generally, electrical energy in physics is measured by power and time. The formula for electrical energy in an electrical circuit is given by
$$\mathrm{Electrical\:energy\:E=Power(P)\times time(t)}$$
Power in an electric circuit is given by
$$\mathrm{P=I^{2}R}$$
$$\mathrm{\therefore Electrical\:energy\:E=I^{2}Rt\:Wh(watt-hour)}$$
A unit of electrical energy is a watt-hour. A watt-hour represents 1-watt power used for 1 hour. Commercially we measure electrical energy in kilowatt-hours. It is commonly referred to as a unit.
$$\mathrm{1\:KWh=1000\:watt\times 3600\:seconds}$$
$$\mathrm{=3.6\times 10^{6}\:watt-second}$$
$$\mathrm{=3.6\times 10^{6}joule}$$
Batteries store the electrical energy which is converted from the process of chemical reactions in it. A chemical solution that can give positive and negative ions is considered an electrolyte. A battery is formed in which two different metal plates are fixed as electrodes. Through chemical reactions, one electrode acts as an anode and the other electrode acts as the cathode, giving electrical energy. Based on how long electricity is produced, batteries are divided into primary batteries and secondary batteries.
A capacitor is a device that helps store particles and electrical energy. It is made up of two dielectric materials separated by a small gap. Capacitors are widely used in many electronic circuits and many scientific and technological fields. Electrical energy is stored in the electric field between the plates of the capacitor. Energy is recovered when the capacitor is discharged. The energy density depends only on the electric field and does not depend on the size of the plates. Capacitors are used to prevent sparking in fuel-ignition systems of automatic machines.
Motors are used to convert electrical energy into mechanical energy. Electric motors are important in modern life. They are used in the water pump, fan, washing machine, juicer, flour mill, etc. A force acting on a conductor placed in a magnetic field causes the conductor to move. This is the principle of the electric motor.
To understand how a motor works, it is necessary to understand how the turning effect occurs on an electric coil placed inside a constant magnetic field. In an electric motor, a simple coil of wire is placed between the two poles of a magnet and also consists of a conductor segment. Currents flow in opposite directions in conductor segments, their kinetics are also opposite according to Fleming’s left-hand rule. Both ends of the coil of wire rotate because the force is in opposite directions. A small device called a split-ring commutator is used to change the direction of the current.
When the gap in the split is connected to the terminals there is no current in the coil. But, as the coil moves, it will continue to move forward and either of the two split rings will come into contact with the carbon brushes. This reversal of current occurs every half cycle and causes continuity in the coil.
The ratio of electrical energy absorbed is called electrical power. Power in an electric circuit is given by
$$\mathrm{P=VI\:\:\:(V=IR)}$$
$$\mathrm{P=I^{2}R}$$
“Watt” is the SI unit of electric power. One watt is the power used by an appliance operating at a one-volt potential difference and one-ampere current. Watt is the smallest unit. Therefore, in practice, we use a larger unit called a kilowatt.
The movement of electrons in an object causes a force. This energy is called electrical energy. Electrical energy is converted into many energy forms. For example, electrodes, amplifiers, electromagnets, light bulbs, and chemical changes. Electrical energy is stored in batteries and capacitors. Motors are used to convert electrical energy into mechanical energy. Electric motors are important in modern life. A unit of electrical energy is a watt-hour. A watt-hour represents 1-watt power used for 1 hour. Commercially we measure electrical energy in kilowatt-hours. The ratio of electrical energy absorbed is called electrical power.
Q1. What is the primary cell?
Ans. Systems that continuously generate electrical energy through irreversible chemical reactions are called primary batteries. Electrostatic force can be obtained by adding electrodes and a suitable electrolyte to the components of a primary battery.
Q2. Define Nuclear Energy
Ans. In a process called nuclear fission, a heavy nucleus ( such as uranium, plutonium, and thorium) can split into lighter nuclei when struck by a slow neutron. When this is done, a huge amount of energy is released. This is called nuclear energy.
Q3. What are the safety measures to save a person in case of electric shock?
Ans.
Turn off the power source causing the shock and disconnect from the key.
Push him away from the contact of the power line with insulating materials.
Q4. What are the uses of capacitors?
Ans. One thing we all know is the camera. When taking pictures, the flash is caused by the energy released from a type of capacitor called a flash capacitor. Capacitors are used in power supplies to reduce power fluctuation and increase the efficiency of the power supply.
Q5. Define electric dipole
Ans. Two equal, different electrons are separated by a small distance from an electric dipole. In many molecules, the center of positive charge and the center of negative charge do not coincide at the same point. Such molecules act like stable electric dipoles.
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