What Is Electricity In Basic Science?

Electricity is the flow of electrons. It is a form of energy that can be carried through wires and be used to power machines and devices. Though electricity seems very commonplace to us today, humans have only been utilizing it for about two centuries.

The early studies of electricity focused on static electricity and electrical phenomena like lightning. It was not until the 1800s that electricity became a technology that could be generated and put to everyday practical use. The invention of the electric battery enabled portable electricity. Soon after, electric generators and motors emerged, allowing electricity to power homes, businesses, and factories.

Today, electricity is fundamental to modern life. It powers all our devices, appliances, machines, and infrastructure that we depend on (lights, heating, cooling, electronics, etc). Our entire economy and society is built around access to electricity.

Table of Contents

Electric Charge

Electric charge is a fundamental property of matter that exists in two types – positive and negative. Atoms consist of subatomic particles called protons, electrons and neutrons. Protons carry a positive electric charge, electrons carry a negative electric charge, and neutrons are electrically neutral. Charge is measured in coulombs. Objects becomes electrically charged through the gain or loss of electrons. Conductors are materials that allow electric charge to flow freely, like metals. Insulators resist the flow of electric charge, like rubber or plastic.

Some key properties of electric charge:

Like charges repel each other, opposite charges attract

Charge is conserved – it cannot be created or destroyed, only transferred from one object to another
Static electricity is an electric charge buildup on an object
Electric fields surround charged particles and exert force on other charged particles

Conductors contain free electrons that can easily move while insulators have tightly bound electrons. This makes conductors able to transmit electric charge but insulators act as barriers. Examples of good conductors are metals like copper. Examples of good insulators are materials like glass, rubber and plastic.

Electric Current

Electric current is the flow of electric charge. It refers to the movement of electrons through a conductive path like a wire or circuit. Electrons flow from areas of high potential energy to areas of low potential energy. This electron flow is what allows electricity to do work.

Electric current is measured in amperes, often shortened to amps. One ampere is defined as one coulomb of charge passing a given point per second. Coulombs measure the amount of electric charge. So electric current measures the rate at which electric charges are moving.

The greater the flow of electrons in a circuit, the greater the electric current. Factors like voltage and resistance affect how strong the current is. Higher voltage forces more electron flow. Higher resistance reduces the flow. Ohm’s Law shows the relationship between current, voltage, and resistance.

Voltage

Voltage is the difference in electric potential energy between two points in a circuit. It measures the “push” or force that moves electric charges from one point to another. Voltage is measured in volts. A volt represents the amount of work needed to move a unit charge, like an electron, between two points.

Voltage is generated by devices like batteries, generators, and solar cells. These devices use chemical, mechanical, or light energy to push charges through a circuit. A 9 volt battery, for example, generates 9 volts of electromotive force to move charges.

Voltage drives the electric current in a circuit. Greater voltage allows more current to flow. Devices like light bulbs are given rated voltages that match how much current they need to operate. Voltage can be increased or decreased using transformers in electric power transmission systems.

Voltage drop is the loss of voltage across resistance in a circuit. Some energy is lost whenever charges move through resistors, converting electrical energy into light, heat, and other forms. The higher the resistance, the larger the voltage drop.

Resistance

Resistance is the property of materials that restricts the flow of electric current. It determines how much current will flow through a component for a given voltage applied across it. Resistance is measured in units called ohms. The higher the resistance value of a component, the more it restricts current flow. Some materials like copper have low resistance and allow current to flow easily, while insulators like rubber have extremely high resistance.

The resistance of a component depends on its physical properties like its length, cross-sectional area, and material composition. Longer and thinner conductors have higher resistance than shorter, thicker conductors. Materials are also intrinsically more or less conductive, based on how their atomic structure interacts with electric current flow. The resistance of most components remains constant, but some devices like thermistors are designed to have resistance that changes along with temperature.

Understanding resistance is crucial for designing efficient and safe electrical circuits and components. High resistance causes power loss in the form of heat, so engineers try to minimize it in power transmission lines. At the same time, large appliances need components with enough resistance to operate at safe current and temperature levels. Ohm’s Law describes the mathematical relationship between current, voltage, and resistance.

Direct Current vs Alternating Current

Electricity can flow in two ways: direct current (DC) and alternating current (AC). In direct current, the electrons flow in one direction from the power source to the device. The flow of electrons is constant. In alternating current, the direction of electron flow constantly changes directions, alternating from forward to reverse. The most common type of alternating current is sinusoidal AC, where the reversals in flow happen in a smooth, sinusoidal pattern.

DC power tends to be suitable for small electronic devices, batteries, and applications where constant power is required. Since the current flows in one direction, it is simpler to use in designs. AC power can operate well over long distances and is used for power grids and supplying electricity to buildings. The constantly changing current allows the voltage to be easily stepped up or down with a transformer. However, AC power is more complex to utilize in electronics due to the reversing flow.

Each type of electricity has its advantages. DC power provides a constant supply while AC power can transmit electricity efficiently over long distances. Engineers consider the needs of the application when determining whether to design for DC or AC power.

Circuits

A circuit is a closed path through which electric current can flow. Components like resistors, capacitors, transistors, and integrated circuits are connected together in a circuit. The connection and arrangement of the components creates a path for the current to flow around.

For a circuit to work, it must form a complete, unbroken loop. If there is a break in the path, current cannot flow. Circuits provide controlled paths for electricity to flow. In a closed circuit, the loop allows electric current to flow from the (+) power to the (-) ground uninterrupted.

The components in a circuit can control the path of the electric current. Things like switches, relays, and transistors can open or close the loop. Resistors can limit the flow, and capacitors can store charges. Together, the components work to control electricity and make circuits perform useful functions.

Circuit diagrams called schematics use symbols to show the components and connections in a circuit. Schematics are like road maps that show how a circuit works. Reading schematics is an important skill for anyone working with electronics and circuits.

Power

Power refers to the rate at which electrical energy is transferred by an electric circuit. It is measured in watts, represented by the symbol W. The greater the power, the more rapidly energy is transferred per unit time. Power depends on two factors:

Current (I) – The amount of charge flowing through a circuit per unit time.

Voltage (V) – The potential difference between two points in a circuit.

Power is calculated using the formula:

P = I x V

Where P is power (watts), I is current (amps), and V is voltage (volts). For example, a device connected to a 120V source with a current of 5A will have an electric power of 600W. Understanding power is crucial for determining the energy consumption and requirements for electrical devices and systems.

Magnetism and Electromagnetism

Magnetism is closely related to electricity. Electric currents and magnetic fields interact with each other and are part of the same fundamental electromagnetic force. Magnetic fields are generated by electric charges in motion. Electric motors and generators work because of the relationship between magnetism and electricity.

A magnetic field is an invisible force field surrounding a magnet or electric current. The magnetic field exerts a force on other magnets and magnetic materials. The direction of the magnetic field is indicated by the orientation of the north and south poles on a magnet or compass.

When an electric current flows through a conductor like a wire, a circular magnetic field forms around the conductor. The right-hand rule shows the direction of this magnetic field relative to the current. The strength of the magnetic field depends on the amount of current. Increased current produces a stronger magnetic field.

Electromagnetic induction uses magnetic fields and electric conductors to generate electric currents. When a conductor moves through a magnetic field, or a magnetic field changes near a conductor, a current is induced in the conductor. Generators use electromagnetic induction to convert mechanical energy into electricity.

The relationship between electricity and magnetism is fundamental. Electricity and magnetism combine to produce electromagnetic waves like radio waves, light, and X-rays. Understanding electromagnetism led to key discoveries in physics and the invention of essential technologies like electric motors, wireless communications, and MRIs.

Safety

Electricity can be very dangerous if not handled properly. There are some important safety precautions to keep in mind when working with electrical equipment or installations:

Precautions

– Avoid working on live circuits whenever possible. Make sure to turn off power and double check that it is off before working on any electrical wiring or devices.

– Wear insulated gloves and use insulated tools when dealing with live wires.

– Keep electrical devices and outlets away from water to avoid electrocution.

– Make sure all electrical appliances and tools are properly grounded.

– Use GFCIs (ground fault circuit interrupters) in areas where water contact is likely, like bathrooms and kitchens.

– Don’t overload circuits with too many appliances or devices plugged in.

– Make sure cords and plugs are in good condition, not damaged or frayed.

– Never put metal objects into outlets or appliances.

Grounding

– Proper grounding provides a safe path for electricity to flow to the ground in the event of a fault or short circuit. This prevents electric shock.

– Electrical panels, appliances, and outlets should all be properly grounded via ground wires and ground rods.

Fuses and Circuit Breakers

– Fuses and circuit breakers are safety devices that break the circuit if there is an overload or short circuit. This prevents fires and damage.