Energy & Electricity at Home
The electricity in a wall socket has usually travelled a long way: from a turbine or solar panel, through transformers and high-voltage lines, down to your home's meter and wiring.
These explainers follow that path, compare the ways we generate and store energy, and explain the safety devices that stop a fault from becoming a fire or a shock.
Start here
How does electricity work?
Electricity works through the flow of electric charge — usually electrons moving through a conductor like a wire. A voltage 'pushes' the charge, current is the rate of flow, and that moving charge delivers energy to power devices.
How does a generator work?
A generator works by spinning a coil of wire inside a magnetic field, which pushes electrons through the wire and creates an electric current. It's essentially an electric motor run in reverse — turning motion into electricity.
How does a turbine work?
A turbine works by letting a moving fluid — wind, water, steam, or hot gas — push against angled blades mounted on a shaft. The flow spins the blades, the shaft turns, and that rotation is used to generate electricity or drive machinery.
Every explainer in this guide · 47
How does a transformer work?
A transformer changes alternating current from one voltage to another using electromagnetic induction between two coils. An alternating current in the primary coil creates a changing magnetic field that induces a voltage in the secondary coil, with the ratio of turns determining the voltage change.
How does a solar panel work?
A solar panel works using the photovoltaic effect: when sunlight hits its silicon cells, it knocks electrons loose, and a built-in electric field pushes those electrons into a current. Wire many cells together and that flow becomes usable electricity.
How does a wind turbine work?
A wind turbine works by using wind to spin large blades, which turn a shaft connected to a generator. The generator converts that spinning motion into electricity — turning the wind's kinetic energy into clean power.
How does a hydroelectric dam work?
A hydroelectric dam works by holding back water at height and letting it fall through turbines. The falling water spins the turbines, which drive generators that make electricity — turning the stored energy of high water into clean power.
How does a nuclear reactor work?
A nuclear reactor works by splitting heavy atoms (nuclear fission) in a controlled chain reaction that releases enormous heat. That heat boils water into steam, which spins a turbine to generate electricity — essentially a giant, atom-powered kettle.
How does geothermal energy work?
Geothermal energy works by tapping the heat stored inside the Earth. Wells bring up hot water or steam from deep underground, which spins turbines to make electricity or heats buildings directly — a clean, always-available energy source.
How does a battery work?
A battery works by turning stored chemical energy into electricity through a reaction that pushes electrons from one terminal to the other. When you connect it in a circuit, that flow of electrons powers your device until the chemicals are used up.
How does a lithium-ion battery work?
A lithium-ion battery works by shuttling lithium ions between two electrodes through a liquid electrolyte. Discharging sends ions one way and pushes electrons through your device; charging forces them back, storing energy for next time.
How does a fuel cell work?
A fuel cell works by combining hydrogen and oxygen to make electricity, with only water and heat as byproducts. Unlike a battery, it doesn't run down — it keeps producing power as long as you supply fuel.
How does a power inverter work?
A power inverter converts direct current (DC) into alternating current (AC) by rapidly switching the DC input on and off to create a changing voltage. This switching action produces a waveform that can be stepped up or down to match the voltage and frequency needed by AC-powered devices.
How does an electrical fuse work?
An electrical fuse is a deliberate weak link in a circuit that melts when too much current flows, breaking the circuit. This prevents overheating and fires by sacrificing a cheap metal strip instead of the wiring or appliance.
How does a circuit breaker work?
A circuit breaker is an automatic switch that trips open when current in a circuit rises above a safe level. It cuts the flow of electricity before overheating wires can start a fire, and can be reset by hand once the fault is fixed.
How does the power grid work?
The power grid is a linked network that carries electricity from power stations to homes by raising it to very high voltage for long-distance transmission, then lowering it in stages for local use. Control centres balance supply against demand every second so the frequency stays steady.
How does a thermal power plant work?
A thermal power plant burns fuel such as coal or gas to boil water into high-pressure steam, which spins a turbine connected to an electrical generator. The used steam is cooled back into water in a condenser and pumped round again in a closed loop.
How does concentrated solar power work?
Concentrated solar power uses mirrors to focus sunlight onto a small receiver, heating a fluid to hundreds of degrees and using that heat to make steam that drives a turbine. Because heat is easier to store than electricity, many plants keep hot molten salt to generate power after sunset.
How does tidal power work?
Tidal power generates electricity from the regular rise and fall of the sea, which is caused by the Moon's and Sun's gravity. Turbines capture energy either from water held behind a barrage and released through it, or from fast tidal currents flowing past underwater rotors.
How does wave energy work?
Wave energy converters capture the up-and-down and back-and-forth motion of ocean waves and turn it into electricity using air turbines, hydraulic systems or direct-drive generators. The waves themselves carry energy that wind has transferred to the sea surface over long distances.
How does a biogas plant work?
A biogas plant works by letting bacteria digest manure, food scraps or crop waste inside a sealed, oxygen-free tank, producing a flammable gas that is mostly methane. The gas is collected for cooking, heating or electricity, and the leftover slurry makes a useful fertiliser.
How do biofuels work?
Biofuels work by turning plant or animal matter into liquid or gaseous fuels, such as ethanol from fermented sugar and biodiesel from vegetable oils, that engines can burn like petrol or diesel. Their carbon was recently captured from the air by growing plants, unlike the ancient carbon in fossil fuels.
How is green hydrogen produced?
Green hydrogen is produced by splitting water into hydrogen and oxygen in an electrolyser powered by renewable electricity such as solar or wind. Because no fossil fuel is burned and only oxygen is released as a by-product, the process emits almost no carbon dioxide.
How do grid-scale batteries store energy?
Grid-scale batteries store energy by charging thousands of rechargeable cells, usually lithium-ion, when electricity is plentiful and discharging them through inverters when demand rises. Racks of cells in shipping-container-sized units connect to the grid through transformers and are run by control software that responds within a fraction of a second.
How does pumped hydro storage work?
Pumped hydro storage works by pumping water uphill from a lower reservoir to an upper one when electricity is plentiful, then letting it flow back down through turbines to generate power when demand is high. It stores energy as gravitational potential energy and accounts for most of the world's grid storage.
How does electrical earthing work?
Electrical earthing works by connecting the metal parts of appliances and wiring to the ground through a low-resistance conductor, so that fault current flows safely into the earth instead of through a person. That surge of fault current also trips a fuse, circuit breaker or residual current device to cut the supply.
How does a short circuit happen?
A short circuit happens when electric current finds an unintended low-resistance path, usually where a live conductor touches neutral or another live wire, bypassing the appliance that normally limits the flow. With almost no resistance, current surges far above normal, producing intense heat and sparks unless a fuse or breaker cuts it off.
How does an electric shock affect the body?
An electric shock affects the body when current passes through it, disrupting the electrical signals that control nerves, muscles and the heart while heating tissue along its path. Harm depends mainly on how much current flows, its route through the body, and how long contact lasts.
How does net metering work?
Net metering lets a home or business with rooftop solar panels send surplus electricity to the grid and receive credit that offsets the power it draws at other times. A bidirectional meter records energy in both directions, and the customer is billed only for the net amount consumed.
Why do power lines use high voltage?
Power lines use high voltage because the same power can then be carried with a much smaller current, and resistive heat loss in the wire rises with the square of the current. Transformers step voltage up at the power station for the long journey and back down near homes for safe use.
Why don't birds get shocked on power lines?
Birds don't get shocked on a power line because both feet touch the same wire at almost the same voltage, so there is no meaningful potential difference to drive current through their bodies. A bird is only electrocuted when it bridges two wires, or a wire and an earthed structure, at once.
How does carbon capture work?
Carbon capture separates carbon dioxide from a gas stream, usually power-plant or factory exhaust, and then compresses it for permanent underground storage or industrial use. Most systems pass the gas through a chemical solvent that grabs CO2, then heat that solvent to release a nearly pure stream of the gas.
How does an oil refinery work?
An oil refinery works by heating crude oil and separating it by boiling point in a distillation column, then chemically reshaping the heavy fractions into lighter, more valuable fuels. Further units remove sulphur and blend the streams into finished products such as LPG, petrol, jet fuel, diesel and bitumen.
How does fracking work?
Fracking, or hydraulic fracturing, works by pumping water, sand and small amounts of chemicals down a well at very high pressure to crack open dense shale rock deep underground. The sand props the new cracks open so trapped natural gas or oil can flow into the well and up to the surface.
How does an LPG cylinder work?
An LPG cylinder works by storing propane and butane as a liquid under pressure, with a pocket of gas above it that feeds the stove. As gas is drawn off through the regulator, some liquid boils to replace it, keeping supply steady until the cylinder is nearly empty.
How does a bicycle dynamo work?
A bicycle dynamo works by using the turning wheel to spin a permanent magnet next to coils of wire, which induces an alternating voltage that powers the lights. Faster riding spins the magnet faster, but the coil's design limits current so the lamp stays reasonably steady across speeds.
How does piezoelectricity work?
Piezoelectricity works because squeezing certain crystals shifts their positive and negative ions slightly apart, creating an electric voltage across the material. The effect also runs in reverse: applying a voltage makes the crystal change shape, which lets the same material sense pressure, make sound or keep precise time.
How does a surge protector work?
A surge protector works by placing a component, usually a metal oxide varistor, across the supply lines that conducts almost nothing at normal voltage but suddenly conducts heavily during a spike. It diverts the excess current away from connected devices, clamping the voltage they see to a safer level.
How does an electrical outlet work?
An electrical outlet works by giving a plug access to two supply conductors, live and neutral, between which an alternating voltage exists, so plugging in completes a circuit through the appliance. A third earth contact provides a safety path that trips the fuse or breaker if a fault energises metal parts.
How does a UPS work?
A UPS works by keeping a battery charged from the mains and, the moment mains power fails or goes out of range, using an inverter to turn that battery's DC into AC for the connected equipment. This bridges outages for minutes, long enough to save work or start a generator.
How does a voltage stabilizer work?
A voltage stabilizer works by sensing the incoming mains voltage and using a transformer to boost it when it sags or buck it when it rises, so the appliance receives a nearly constant voltage. Relay models switch between transformer taps in steps, while servo models move a brush along a winding smoothly.
How does an electricity meter work?
An electricity meter works by measuring the voltage and current supplied to a building, multiplying them to find power, and adding that power up over time as energy in kilowatt-hours. Older meters did this with a spinning aluminium disc, while modern electronic meters use a chip that samples the signals thousands of times per second.
How does a smart meter work?
A smart meter works by measuring electricity use like a standard electronic meter, recording it in short intervals, and sending those readings automatically to the utility over a communications network. Two-way communication also lets the utility update tariffs, switch supply on or off remotely and run prepaid accounts.
How does a capacitor work?
A capacitor stores electrical energy in an electric field between two conducting plates separated by an insulator called a dielectric. When voltage is applied, charge builds up on the plates until the capacitor matches the supply voltage, and it releases that energy when connected to a load.
How does a resistor work?
A resistor works by restricting the flow of electric current, turning some electrical energy into heat as electrons collide with atoms in its material. The amount of resistance, measured in ohms, sets how much current flows for a given voltage, following Ohm's law.
How does a diode work?
A diode works as a one-way valve for electric current, letting it flow easily in one direction and blocking it in the other. It does this with a junction between two differently doped layers of semiconductor, usually silicon, which forms a barrier that only a forward voltage can overcome.
How does insulation keep a house warm?
Insulation keeps a house warm by slowing the flow of heat from the warm interior to the colder outdoors through walls, roofs, floors and windows. It traps air or gas in tiny pockets that conduct heat poorly and cannot circulate, so the heating system replaces less lost energy.
Key ideas behind them
What is energy?
Energy is the capacity to do work — to move, heat, light, or change things. It comes in many forms (kinetic, heat, light, chemical, electrical) and can be converted between them, but it can never be created or destroyed, only transformed.
What is electricity?
Electricity is energy carried by the movement of electric charge, usually electrons flowing through a material. It powers nearly all modern technology — from light bulbs to phones — by pushing charged particles through circuits to do useful work.
What is renewable energy?
Renewable energy comes from natural sources that replenish faster than we use them — sunlight, wind, water, and heat from the Earth. Unlike fossil fuels, it doesn't run out and produces little or no carbon.
What is nuclear energy?
Nuclear energy is the energy released when atomic nuclei are split (fission) or fused (fusion). Power plants use controlled fission of uranium to boil water, spin turbines, and generate electricity with almost no carbon emissions.
What is Ohm's law?
Ohm's law is the basic rule of electric circuits: the current flowing through a conductor is proportional to the voltage across it and inversely proportional to its resistance. In short, V = I × R — voltage equals current times resistance.
What is magnetism?
Magnetism is a force that makes certain materials attract or repel each other, created by the motion of electric charges. A magnet has two poles — north and south — and is surrounded by an invisible magnetic field that pulls on magnetic materials like iron.
What are the laws of thermodynamics?
The laws of thermodynamics describe how energy behaves. In short: energy can't be created or destroyed, only transformed; systems naturally move toward disorder (entropy); and you can never reach absolute zero. They govern everything from engines to the universe.
What are kinetic and potential energy?
Kinetic energy is the energy of motion; potential energy is stored energy waiting to be released, often due to position. A ball at the top of a hill has potential energy that turns into kinetic energy as it rolls down — energy converting from one form to another.
What is static electricity?
Static electricity is a buildup of electric charge on a surface, created when materials rub together and transfer tiny particles called electrons. It's why a balloon sticks to your hair and why you sometimes feel a small shock touching a doorknob.
हिंदी में पढ़ें: बिजली कैसे काम करती है? · जनरेटर कैसे काम करता है? · ट्रांसफार्मर कैसे काम करता है? · सोलर पैनल कैसे काम करता है? · बैटरी कैसे काम करती है? · पावर ग्रिड कैसे काम करता है? · थर्मल पावर प्लांट कैसे काम करता है? · बायोगैस प्लांट कैसे काम करता है?
Frequently asked questions
Why is electricity sent over high-voltage lines?
For the same power, a higher voltage means a smaller current, and less current means less energy lost as heat in the wires. Transformers step the voltage up for long-distance lines and back down for homes.
What is the difference between AC and DC?
In direct current (DC) charge flows one way, as from a battery. In alternating current (AC) it reverses direction many times a second (50 times in India and the UK, 60 in the US), which makes it easy to change voltage with transformers.
Can renewable energy run a whole grid?
It can supply a large share, but sun and wind vary, so grids pair them with storage such as batteries and pumped hydro, flexible power plants, and links to neighbouring grids.