physics

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A diagram of a cylindrical vessel containing gas, with a movable piston held down by a weight. Countless small dots beneath the piston represent gas particles in rapid, random motion, illustrating Bernoulli's model of gas pressure.

A man wearing glasses and a blue turtleneck holds a globe patterned like a soccer ball, with stadium and physics equations in the background and text above stating Science of Soccer.

illustration of Robert Hooke's law of elasticity of materials

Illustration of a space-based long-range interferometer system for detecting gravitational waves, showing three spacecraft in triangular formation exchanging laser beams, with labeled components including interferometers, solar arrays, thrusters, and the path of gravity waves, as well as Earth's position and orbital path in the background.

A grid representing spacetime is distorted by three spheres of different sizes, illustrating how massive objects curve spacetime according to general relativity.

Three thermometers compare temperature scales, showing absolute zero, freezing, and boiling points of water in Celsius, Fahrenheit, and Kelvin, with labeled values for each scale.

Two-panel diagram illustrating Brownian motion. The top shows a Brownian particle among randomly moving blue molecules, while the bottom highlights uneven molecular collisions on the particle's surface, causing its movement.

Diagram of the electromagnetic spectrum with labeled sections for radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays, each paired with an example use and corresponding image.

$Diffraction grating$

Diagram of the Millikan oil-drop experiment showing a chamber with oil droplets sprayed from an atomizer, falling between two charged metal plates. A light source and viewing microscope are used to observe the droplets, which are influenced by electric and ionizing radiation to measure their charge.

At a Glance

$Diffraction grating$

physics summary

physics: Media

science

Videos

A man wearing glasses and a blue turtleneck holds a globe patterned like a soccer ball, with stadium and physics equations in the background and text above stating Science of Soccer.

How Physics Makes “Impossible” Soccer Kicks Possible

You can't bend it like Beckham without a little help from physics.

Video: Encyclopædia Britannica, Inc.

Robert Millikan's method for measuring the charge of an electron

Robert Millikan's method for measuring the charge of an electron

Millikan oil-drop experiment.

Video: Encyclopædia Britannica, Inc.

quantum mechanics and probability

quantum mechanics and probability

Brian Greene explains how the revolutionary idea of quantum mechanics is that reality...

Video: © World Science Festival (A Britannica Publishing Partner)

Know about the common misconceptions in physics like how gravity affects light, the shape of the earth, and measuring velocity in special relativity

Know about the common misconceptions in physics like how gravity affects light, the shape of the earth, and measuring velocity in special relativity

Learn about common physics misconceptions such as how light is affected by gravity...

Video: © MinutePhysics (A Britannica Publishing Partner)

Images

A diagram of a cylindrical vessel containing gas, with a movable piston held down by a weight. Countless small dots beneath the piston represent gas particles in rapid, random motion, illustrating Bernoulli's model of gas pressure.

Bernoulli model of gas pressure

As conceived by Daniel Bernoulli in Hydrodynamica (1738), gases consist...

Encyclopædia Britannica, Inc.; based on Daniel Bernoulli, Hydrodynamica (1738)

illustration of Robert Hooke's law of elasticity of materials

illustration of Robert Hooke's law of elasticity of materials

Illustration of Hooke's law of elasticity of materials, showing the stretching of...

Photos.com/Jupiterimages

Illustration of a space-based long-range interferometer system for detecting gravitational waves, showing three spacecraft in triangular formation exchanging laser beams, with labeled components including interferometers, solar arrays, thrusters, and the path of gravity waves, as well as Earth's position and orbital path in the background.

Laser Interferometer Space Antenna (LISA)

Laser Interferometer Space Antenna (LISA), a Beyond Einstein Great Observatory, is...

Encyclopædia Britannica, Inc.

A grid representing spacetime is distorted by three spheres of different sizes, illustrating how massive objects curve spacetime according to general relativity.

curved space-time

The four dimensional space-time continuum itself is distorted in the vicinity of...

Encyclopædia Britannica, Inc.

Three thermometers compare temperature scales, showing absolute zero, freezing, and boiling points of water in Celsius, Fahrenheit, and Kelvin, with labeled values for each scale.

temperature scales

Standard and absolute temperature scales.

Encyclopædia Britannica, Inc./Patrick O'Neill Riley

Two-panel diagram illustrating Brownian motion. The top shows a Brownian particle among randomly moving blue molecules, while the bottom highlights uneven molecular collisions on the particle's surface, causing its movement.

Brownian particle

(Left) Random motion of a Brownian particle and (right) random discrepancy between...

Encyclopædia Britannica, Inc.

Diagram of the electromagnetic spectrum with labeled sections for radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays, each paired with an example use and corresponding image.

Electromagnetic radiation

Radio waves, infrared rays, visible light, ultraviolet rays, X-rays, and gamma rays...

Encyclopædia Britannica, Inc.

$Diffraction grating$

Diffraction grating

Spectrum of white light by a diffraction grating. With a prism, the red end of the...

Courtesy of Bausch & Lomb, Rochester, N.Y.

Diagram of the Millikan oil-drop experiment showing a chamber with oil droplets sprayed from an atomizer, falling between two charged metal plates. A light source and viewing microscope are used to observe the droplets, which are influenced by electric and ionizing radiation to measure their charge.

Millikan oil-drop experiment

Between 1909 and 1910 the American physicist Robert Millikan conducted a series of...

Encyclopædia Britannica, Inc.

transistor

transistor

The first transistor, invented by American physicists John Bardeen, Walter H. Brattain,...

© Windell Oskay, www.evilmadscientist.com (CC BY 2.0)

Simple diagrams of protons, neutrons, and pions display yellow quark and green antiquark spheres connected by purple ribbon-like gluons, illustrating the internal structure of these atomic particles.

protons, neutrons, pions, and other hadrons

Very simplified illustrations of protons, neutrons, pions, and other hadrons show...

Encyclopædia Britannica, Inc.

Diagram comparing atomic structure models: on the left, the Bohr model shows electrons orbiting a nucleus in labeled energy levels; on the right, wave mechanics depict electron wave patterns around the nucleus.

Bohr theory

The Bohr theory sees an electron (left) as a point mass occupying certain energy...

Encyclopædia Britannica, Inc.

A diagram showing an X-ray photon colliding with an electron, causing the electron to scatter and the photon to emerge with a longer wavelength, illustrating the Compton effect.

Compton effect

When a beam of X-rays is aimed at a target material, some of the beam is deflected,...

Encyclopædia Britannica, Inc.

Two graphs illustrate effects of relativity as velocity approaches the speed of light: the left graph shows time dilation increasing sharply, while the right graph shows length contraction decreasing, both as functions of velocity.

length contraction and time dilation

As an object approaches the speed of light, an observer sees the object become shorter...

Encyclopædia Britannica, Inc.

Diagram showing the sequence of uranium nucleus fission after being struck by a neutron: the nucleus absorbs the neutron, deforms, splits into fragments, releases more neutrons and gamma rays, and emits beta particles as the fragments decay. Labels identify neutrons, protons, beta particles, and gamma rays, with accompanying explanatory text.

Fission

Sequence of events in the fission of a uranium nucleus by a neutron.

Encyclopædia Britannica, Inc.

laser-activated fusion

laser-activated fusion

Interior of the U.S. Department of Energy's National Ignition Facility (NIF), located...

U.S. Department of Energy

Computer-generated diagram showing particle tracks from a proton-antiproton collision at the center of the UA1 detector at CERN, with labeled paths for electron and positron.

proton-antiproton collision

Tracks emerging from a proton-antiproton collision at the centre of the UA1 detector...

David Parker—Science Photo Library/Photo Researchers

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