Energy describes a system’s capacity to do work or transfer heat and radiation. Unit: Joule (J). Energy is transferred and converted; total energy is conserved in an isolated system.
A photon is a quantum of the electromagnetic field, a quantum of light. It has no electric charge and zero rest mass, yet carries energy and momentum. In vacuum, light propagates at c. Photons exhibit quantum wave and particle properties.
Eγ = hν = hc/λ: h is Planck’s constant, ν the frequency and λ the vacuum wavelength. Shorter wavelength means more energy per photon. More light at the same wavelength means more photons per unit time, not more energy per photon.
The gold wave packet represents a photon; an arrow only indicates propagation direction. The drawing does not depict its shape or trajectory. During absorption, a photon can excite an existing electron: an electron–hole pair forms, not a newly created electron. The solar-cell junction field separates the carriers. The photon has then been absorbed. Motion is greatly slowed down.
Sources: DOE · Photons · OpenStax · Photon energy
What happens? An uncharged neutron strikes U-235. The excited U-236 nucleus deforms and splits. The larger Ba-141 nucleus forms on the left, Kr-92 on the right. Three free neutrons depart along green trails; gold waves indicate γ radiation. Most released energy becomes fragment motion and heats the material as the fragments slow down.
Neutrons may trigger further fissions: a chain reaction. Not every neutron causes fission; some escape or are absorbed in other reactions. Additional uranium atoms are not shown here.
Sources: DOE · Nuclear fission · RSC · Uranium · RSC · Barium · RSC · Krypton
A cell membrane is a selectively permeable lipid bilayer. Ion channels allow passive transport down electrochemical gradients; ATP-driven pumps can work against them.
Vm = φinside − φoutside is an electric potential difference, not energy. The electrical energy difference for charge q is ΔEelectrical = q·Δφ. For ions, concentration differences also matter. An action potential uses stored electrochemical gradients; ATP-driven pumps maintain them over time. Photon absorption belongs to module G; no light-gated channel is modeled here.
Two lipid layers form a membrane: polar, hydrophilic heads face the water outside and inside. The two hydrophobic fatty-acid tails point towards one another inside the membrane. The drawing shows an animal cell membrane.
Green inside the lipids: cholesterol, which helps regulate fluidity. Pink external chains: glycolipids and glycoproteins for recognition and cell contacts. Blue: channel proteins; purple: ATP-driven pump. Other proteins lie on the surface; the cytoskeleton supports the inner side. Membrane proteins have different functions.
Vm is measured inside relative to outside. The timeline represents 0–12 model milliseconds, shown very slowly. Pump motion uses a separate, symbolic timescale. Pump: 3 Na⁺ out / 2 K⁺ in / 1 ATP. Na⁺ and K⁺ remain positive ions in both compartments; +/− signs indicate a small local charge separation at the membrane.
Absorption: photon disappears → electron is excited + a hole remains. Energy is transferred. The n-layer does not block all light: deeper layers can also absorb it. Reflection creates no pair here. The contact grid leaves windows for light.
Common emitter: more light → greater collector current → lower output voltage. Purple: external supply. This is an illustrative equivalent model, not a measured characteristic of a specific device.
Solaristor: stored polarization of the transport layer
Symbolic write pulse through the same two contacts. The state persists in darkness. The current comparison is qualitative, not measured solaristor data.
Try opening the circuit, setting light to 0 or increasing λ beyond the absorption threshold. Holes are red rings, moving electrons blue spheres and light quanta gold. The solaristor layers are absorber and transport layers; n/p labels apply only to the silicon solar cell.
At 0 K = −273.15 °C this classical model shows no motion. Quantum physics allows zero-point motion even in the ground state. Water boils at about 100 °C at 1 atm (1013.25 hPa); boiling temperature depends on pressure. The cluster shows generic atoms, not H₂O molecules. The system as a whole is at rest. Internal thermal motion is greatly enlarged and slowed down. Electron rings are a simplified atomic model. Temperature controls the teaching animation; total rest mass remains separately adjustable.
Warm ground-level air → cold cloud regions → charge separation → cloud-to-ground discharge → heat / fulgurite.
Orange arrows show rising warm, moist air; light-blue arrows show cooler downdrafts. The +/− signs represent electric charges. Temperature contrast and electric charge are different quantities. This is a simplified storm model, not a weather or atmospheric-front simulation.
Model values: initial temperature 20 °C; mean specific heat cₚ = 1000 J/(kg·K); simplified melting threshold 1710 °C; latent heat L = 150 kJ/kg. These are teaching approximations, not an accurate soil simulation. Heat conduction, moisture, evaporation and chemical changes are omitted. Predictions above 2500 °C are flagged as outside the model range. Fulgurites form mainly by vitrification; remaining quartz grains stay crystalline.
Elastic potential energy: Here this means the elastic potential energy of an ideal spring. x is its displacement from the unloaded length. For a Hookean spring, E = ½kx². Stretching and compressing store energy.
Kinetic energy: Energy due to motion. During acceleration, work is converted into kinetic energy.
Rest energy: E₀ = mc² is associated with the mass of a body at rest. It is not automatically all available for use.
Nuclear energy: Differences in nuclear binding produce a difference in total rest mass before and after a reaction. This energy difference is transferred, for example, into motion and radiation.
Chemical energy: Differences between the energies of chemical states. The sodium/chlorine example shows electron transfer; the full reaction’s energy balance also includes ionization, electron capture and formation of the ionic lattice.
Electrical energy: Energy in electric fields or transferred by electrical work. High voltage alone does not specify energy; charge, or current and duration, is also needed.
Sources: OpenStax · Membrane components · PVEducation · Photon absorption · PVEducation · Carrier collection · onsemi · Phototransistor circuits · OpenStax · Action potential · OpenStax · ATP and pump transport · Solaristor · Reference article · Solaristor · Original research · DOE · Solar cell · DOE · Carriers and losses · AME2020 · Nuclear masses · NWS · Storms and charge separation · NIST · Temperature units · Zero-point motion · Nobel · Brownian motion · NIST · Quartz heat capacity · Fulgurite experiment · USGS · Fulgurite tubes · Fulgurite · Reference article · DOE · Nuclear fission · DOE · Relativity · RSC · Sodium and chlorine · NWS · Lightning. This application works offline.