Voltage
The electric force known as voltage is what moves the free electrons from one atom to another. Voltage is a unit of measurement for the electrical energy differential between two circuit components; the greater the energy difference, the higher the voltage. The equipment known as voltmeter is used to measure the voltage.
Current
The Current is the rate at which electrons move through a circuit. It is electricity in motion. It measures how many electrons can move freely through a conductor-like substance.The magnitude of current increases as more electron flows. Amperes, or simply “amp are the units used to measure electrical current. The symbol for amps is A. Mathematically. Current= Charge Time = Q/t = Coulomb Second
1 Ampere Current
The current flowing through a conductor is stated to be 1 Ampere current when Coulomb of charge passes through the conductor in 1 second. Amperes are comparable to the flow of electricity via a wire or the volume of water through a hose during a predetermined period of time.
Resistance:
Resistance is the ability of a substance to resist the flow of current through it. It is denoted by ‘R’ and its SI unit is ohm ”. The resistance of a conductor can be calculate using the mathematical relation, Resistance= Potential Difference/ Current or, R = V/I Here, if the potential difference V= 1 volt and the current in the conductor is 1 ampere then the resistance of the conductor becomes 1 ohm.
i.e. 1ohm = 1 volt l amp Thus, 1 ohm is the resistance of the conductor, when I ampere of current flows through a conductor under a potential difference of 1 volts.
Movement of Electrons in a Conductor
Drift Velocity:
Drift velocity is the term used to describe the average speed that a particle, such as an electron, can reach due to the presence of an electric field. Since it is assumed that the particles are travelling along a plane, the velocity can alternatively be referred to as the axial drift velocity.
When connected to a battery, the electric field created by the battery accelerates the free electrons, giving them more speed and energy. The ion is ultimately the winner (of energy) in this collision because the transit is not smooth and the electrons bump into the lattice ion. These collisions cause the temperature of the metal to rise because, as we all know, the energy of a body’s vibrations is connected to its temperature. Electrons eventually begin to drift in a specific direction as a result of their energy being lost in collisions and being accelerated by an electric field. (Even if the electrons’ actual speed is irregular, the overall result is electron drift.)Thus, the motion caused by random collisions and the motion of the conducting electrons in an electric field are linked. When all free electrons are taken into account, their random motion averages to zero and has no bearing on the drift speed. Therefore, the electrons’ response to the electric field is the only factor contributing to the drift speed.
Sources of Electricity
Hydro:
The term hydro means water. Hydropower is a method of producing electricity using water. One of the earliest and most significant types of renewable energy, hydropower or hydroelectric power harnesses the naturally occurring flow of moving water to produce electricity.
The majority of hydroelectric plants use dams to store their water, and the amount water that goes out is controlled by a gate or valve. More energy can be produced the higher the dam is elevated. The water gains potential energy just before crossing the dam, and as it runs downhill, this potential energy is transformed into kinetic energy. A turbine is rotated by the water, and the turbine is connected to an electric generator the produces electricity for the end user.
Nuclear Fission/Fusion:
Atoms split apart to produce smaller atoms during nuclear fission, which release energy. Inside a nuclear power plant’s reactor, fission occurs. The core of the reactor is where the uranium fuel is located.
The idea behind fusion power is to use the heat produced by nuclear fusion reactions create released in the process. Fusion reactors are machines made to harness this energy.
Wind:
One of the most rapidly expanding renewable energy sources is wind power. Worldwide usage is increasing, because prices are decreasing. Utilizing the kinetic energy by moving air, wind energy is used to generate electricity using wind turbines or other wind energy conversion technologies, this is converted into electrical energy. When the wind strikes the turbine blade, it is rotated and the shaft connected with it is also rotated. By rotating a shaft that is attached to the generator, this converts kinetic energy into rotational energy, providing electrical energy via electromagnetism.
Thermal
in thermal power plants, electricity is produced by using heat. Steam is used to power most thermal power facilities. Usually, a turbine is made to spin by directing steam created from heated water across its blades. The turbine is frequently used to power an electrical generator or performed other tasks, such as rotating a ship’s propeller.
Solar
Solar electricity is generated by capturing sunlight using photovoltaic (PV) cells. These cells, typically made from semiconductor materials like silicon, absorb photons from sunlight, causing electrons to become excited and move. This movement of electrons creates an electric current, which can be harnessed for power. The PV cells are grouped together in solar panels. When sunlight hits the panels, the PV cells convert the light energy directly into direct current (DC) electricity. This DC electricity is often converted into alternating current (AC) using an inverter, as AC is the standard used in homes and businesses. Solar power systems can be standalone, providing electricity directly to a location, or they can be connected to the grid, allowing excess power to be fed back into the electrical grid. This process not only provides renewable energy but also contributes to reducing greenhouse gas emissions and dependency on fossil fuels.
Conventional Direction of electrical current and its use
The conventional direction of electrical current is defined as the flow of positive charge from the positive terminal to the negative terminal of a power source, such as a battery. This concept originated in the 18th century before the discovery of the electron and the understanding that actual charge carriers in most circuits are negatively charged electrons, which move in the opposite direction. In engineering and physics, the use of conventional current direction aids in standardizing communication, making it easier to share designs and collaborate across the industry. It also aligns with the established mathematical and theoretical frameworks used to analyze electrical circuits, ensuring consistency and clarity in the field.
Electrical Resistance and its unit
Electrical resistance is a measure of the opposition that a material offers to the flow of electric current. It quantifies how much a material resists the movement of electrons through it. The greater the resistance, the less current will flow for a given applied voltage.
The unit of electrical resistance is the ohm, symbolized by the Greek letter omega (Ω). One ohm is defined as the resistance that occurs when a one-volt potential difference causes a current of one ampere to flow through a conductor. The relationship between voltage (V), current (I), and resistance (R) is given by Ohm’s Law, which states:
R= V/I
This equation implies that the resistance in a circuit can be calculated if the voltage and current are known.
Use and Application of Resistance in a circuit
Use of Resistor in Circuit Functions:
Resistors are fundamental components in electronic circuits, serving to limit or regulate the flow of electric current. They are used to protect sensitive components from receiving too much current, to create specific voltage drops, and to set operating conditions for other components. By providing precise resistance values, they help control the behavior of the circuit.
Use of Resistor in LED Circuits:
When used with Light Emitting Diodes (LEDs), resistors limit the current to prevent damage to the LED. LEDs have a maximum current rating, and exceeding this can destroy the LED. A resistor in series with the LED ensures that the current stays within safe limits. The resistor value is chosen based on the supply voltage, the forward voltage of the LED, and the desired current.
Use of Resistor in Transistor Circuits:
In transistor circuits, resistors are used to set biasing conditions, ensuring the transistor operates in the correct region (active, cutoff, or saturation). For example, in a common-emitter amplifier, a resistor in the emitter leg helps stabilize the operating point against variations in transistor parameters and temperature.
Use of Resistor for Heating:
Resistors convert electrical energy into heat through the process of Joule heating. When current flows through a resistor, power is dissipated as heat. This principle is used in devices such as electric heaters, toasters, and incandescent light bulbs. The resistor material and design are chosen to maximize heat production and ensure durability.
Use of Resistor in Timing Circuits:
Resistors are critical in timing circuits, such as those using capacitors and the 555 timer IC. The resistor and capacitor together determine the timing interval. For instance, in an RC timing circuit, the resistor controls the rate at which the capacitor charges or discharges, thus setting the timing period of oscillations or delays.
Use of Resistor for Dividing Voltage:
Voltage dividers are circuits that use two or more resistors in series to produce a fraction of the input voltage. This is useful for creating reference voltages, scaling down voltages for measurement, or providing bias voltages. The output voltage is determined by the ratio of the resistances, making it a simple yet effective way to control voltage levels within a circuit.
Classification of object on basis of resistance
Conductor:
Conductors are materials that allow the free flow of electric current due to the presence of a large number of free electrons. Conductors have very low electrical resistance, which means they allow electric current to pass through them easily. They have a high density of free electrons that can move easily under the influence of an electric field. Common conductors include metals such as copper, aluminum, silver, and gold. Conductors are widely used in electrical wiring, electronic components, and power transmission. Copper is a well-known conductor used extensively in electrical wiring due to its excellent conductivity and relatively low cost.
Semiconductors:
Semiconductors are materials whose electrical conductivity is intermediate between that of conductors and insulators. Their conductivity can be modified by adding impurities (a process called doping) or by changing environmental conditions such as temperature and light. Semiconductors have higher resistance than conductors but lower than insulators. The electrical properties of semiconductors can be controlled by doping with elements that either add free electrons (n-type) or create holes (p-type) that act as positive charge carriers. Common semiconductor materials include silicon, germanium, and gallium arsenide. Semiconductors are the foundation of modern electronics, used in devices such as diodes, transistors, and integrated circuits. Silicon is the most widely used semiconductor material, forming the basis of most electronic devices, including computer chips and solar cells.
Insulators:
Insulators are materials that resist the flow of electric current due to the absence of free electrons or charge carriers. Insulators have very high electrical resistance, preventing the free flow of electric current. They have very few free electrons, which makes it difficult for electric current to pass through. Common insulators include rubber, glass, plastic, and ceramic. Insulators are used to protect and isolate electrical conductors and components, ensuring safety and preventing short circuits. Rubber is commonly used as an insulating material for coating electrical wires, providing protection against electrical shock and damage.
Factor affecting resistance:
The resistance of a conductor is influenced by several factors: the length of the conductor, the cross-sectional area of the conductor, the temperature of the conductor, and the nature of the conducting material. Here’s a detailed explanation of how each factor affects resistance:
Length of the Conductor:
Resistance is directly proportional to the length of the conductor.
R
The longer the conductor, the more collisions electrons will have with the atoms in the material as they move through it. This increased number of collisions leads to higher resistance. A wire that is twice as long as another wire of the same material and cross-sectional area will have twice the resistance.
Cross-Sectional Area of the Conductor:
Resistance is inversely proportional to the cross-sectional area of the conductor.
R
A larger cross-sectional area provides more pathways for electrons to travel through, reducing the number of collisions per unit area. This results in lower resistance.
A wire with twice the cross-sectional area of another wire of the same material and length will have half the resistance.
Temperature of the Conductor:
For most conductors, resistance increases with an increase in temperature.
R
As temperature increases, the atoms in the conductor vibrate more vigorously. These vibrations increase the likelihood of collisions between the electrons and atoms, thereby increasing resistance. However, for some materials, particularly semiconductors, resistance decreases with an increase in temperature due to increased charge carrier density. A copper wire’s resistance will increase if it is heated, as the thermal agitation of atoms makes it harder for electrons to flow.
Nature of the Conducting Material:
Resistance depends on the material’s intrinsic properties, characterized by its resistivity (ρ).
Different materials have different numbers of free electrons and atomic structures, which affect how easily electrons can flow. Materials with low resistivity, like copper and silver, have low resistance, while materials with high resistivity, like nichrome and constantan, have higher resistance. Silver has a lower resistivity compared to iron, so a silver wire will have lower resistance than an iron wire of the same length and cross-sectional area.