Important Effects in Physics
1. Doppler Effect
The apparent change in the frequency of sound/light percieved by an observer when there is a relative motion between the observer and the wave source.
The Doppler effect is named after the Austrian physicist Christian Doppler.
2. Photoelectric Effect
The ejection of electrons from a mettal surface when light of frequency above a threshold frequency is incident on it.
The photoelectric effect was explained in 1905 by Albert Einstein who correctly concluded that light must be made of quanta or packets of energy.
3. Magnus Effect
It is the generation of a sidewise force on a spinning cylindrical or spherical solid immersed in a fluid (liquid or gas) when there is relative motion between the spinning body and the fluid.
Named after the German physicist and chemist H.G. Magnus, it is responsible for the “curve” of a served tennis ball or a driven golf ball.
4. Compton Effect
When a monochromatic beam of high frequency (lower wavelength) radiation (e.g., X-rays and g-ray) is scattered by a substance, the scattered radiation contains two types of wavelengths one having same wavelength as that of incident radiation while the other having the wavelength greater than that of incident radiations.
This effect is named after A. H. Compton.
5. Raman Effect
The change in the wavelength of light that occurs when a light beam is scattered by molecules. When a beam of light traverses a transparent sample of a chemical compound, a small fraction of the light emerges in directions other than that of the incident (incoming) beam. Most of this scattered light is of unchanged wavelength. A small part, however, has wavelengths different from that of the incident light; its presence is a result of the Raman effect.
The effect is named after Indian physicist C.V.Raman
6. Tyndall Effect
Scattering of a beam of light by a medium containing small suspended particles—e.g. smoke or dust in a room, which makes visible a light beam entering a window. The effect is named for the 19th-century British physicist John Tyndall,
7. Hall Effect
The production of a potential difference across an electrical conductor when a magnetic field is applied in a direction perpendicular to that of the flow of current.
This effect is named after Edwin Hall.
If the conductor is very thin, the temperature very low, and the magnetic field very strong, the conductivity makes discrete jumps, which is known as the quantum Hall effect.
8. Seebeck Effect
Production of an electromotive force (emf) in a loop consisting of at least two dissimilar conductors when two junctions are maintained at different temperatures.
The German physicist Thomas Johann Seebeck discovered the effect(1821).
9. Peltier-effect
When electric current flows through a junction connecting two materials heat will be emited or absorbed at the junction.
Peltier effect is the reverse phenomenon of the Seebeck effect
10. Thomson Effect
The generation of reversible heat when an electrical current is sent through a conducting material that is subjected to a temperature gradient.
11. Bridgman effect
When an electric current passes through an anisotropic crystal, there is an absorption or liberation of heat because of the non-uniformity in current distribution.
The Bridgman effect , also called the internal Peltier effect is named after P. W. Bridgman.
12. Joule-Thomson effect
The change in temperature that accompanies expansion of a gas without production of work or transfer of heat.
This phenomenon often is utilized in liquefying gases.
13. Piezo electric effect
The ability of certain materials to generate an electric charge in response to applied mechanical stress.
14. Casimir Effect
The attraction between two uncharged metal plates at close proximity. This effect is named after Hendrik Casimir. It is created by quantum fluctuations that create a pressure even in vacuum. This pressure is lower between the plates than outside of them, so that the two plates are pushed towards each other.
15. Meissner Effect
The expulsion of a magnetic field from a superconductor during its transition to the superconducting state when it is cooled below the critical temperature
It was discovered by Walther Meissner and Robert Ochsenfeld in 1933.
16. Zeeman effect
The splitting of a single spectral line into two or more lines of different frequencies observed when radiation originates in a magnetic field
17. Stark effect
The splitting of spectral lines observed when the radiating atoms, ions, or molecules are subjected to a strong electric field.
This is the electric analogue of the Zeeman effect. It was discovered by a German physicist, Johannes Stark (1913).
18. Tunnel Effect
Quantum effect allows a particle that is trapped in a potential well to escape. In quantum mechanics the wave-function of the particle can leak out of the potential well and this means that there is a small, but nonzero, probability that a quantum particle can be outside the well.
19. Tennis Racket Effect/Dzhanibekov effect
If a three-dimensional object is thrown with a spin, then the spin around the shortest and longest axes will be stable, but that around the intermediate third axis will not be. The typical example for the spinning object this is a tennis racket, hence the name. It’s also known as the intermediate axis theorem or the Dzhanibekov effect.
20. Mössbauer effect
Nuclear process permitting the resonance absorption of gamma rays. It is made possible by fixing atomic nuclei in the lattice of solids so that energy is not lost in recoil during the emission and absorption of radiation. Discovered by the German-born physicist Rudolf L. Mössbauer in 1957.
21. Auger effect
The phenomenon in which the filling of an inner-shell vacancy of an atom is accompanied by the emission of an electron from the same atom. When a core electron is removed, leaving a vacancy, an electron from a higher energy level may fall into the vacancy, resulting in a release of energy. Although most often this energy is released in the form of an emitted photon, the energy can also be transferred to another electron, which is ejected from the atom; this second ejected electron is called an Auger electron
22. Debye-Sears effect
In the Debye-Sears effect light is diffracted by a standing wave pattern of soundwave. Sound wave acts as a transmissive diffraction grating. The light is broken up into a number of different output beams. When the light beam is in the same direction as the acoustic wave the refracted light (but not the transmitted light) is shifted in frequency.
When ultrasonic waves are generated in a liquid in a rectangular vessel, the wave can be reflected from the walls of the vessel. The direct and reflected waves are superimposed, forming a standing wave. The density of the liquid at a node is more than the density at an antinode. Hence, the liquid acts as a diffraction grating to a parallel beam of light passed through the liquid at right angles to the wave.
23. Faraday effect
The rotation of the plane of polarization (plane of vibration) of a light beam by a magnetic field. Michael Faraday first observed the effect when studying the influence of a magnetic field on plane-polarized light waves. He discovered that the plane of vibration is rotated when the light path and the direction of the applied magnetic field are parallel. The Faraday effect occurs in many solids, liquids, and gases.
24. Butterfly Effect
For some non-linear systems even slight changes in initial conditions can lead to very large changes in the future. Even a tiny change, like the flap of a butterfly’s wings, can make a big difference for the weather later. This is the butterfly effect.
25. Barkhausen effect
The Barkhausen effect is a name given to the noise in the magnetic output of a ferromagnet when the magnetizing force applied to it is changed.
Discovered by German physicist Heinrich Barkhausen in 1919, the effect is caused by rapid changes of size of magnetic domains.
26. Aharonov–Bohm Effect
A quantum phenomenon in which a particle is affected by electomagnetic fields even when traveling through a region of space in which both electric and magnetic fields are zero. The Aharonov-Bohm effect says that the wave-function of a charged particle like an electron in an electromagnetic field obtains a phase shift from the potential of the background field.
The effect arises because the addition of a potential results in the introduction of a phase in the wavefunction of the electron. This phase can be detected by measuring the quantum mechanical interference between electrons that have taken two different paths from a source to a detector. If these paths travel through regions with different local values of gauge potential, then a difference in phase will alter the interference pattern measured.
This effect was proposed in 1959 by Yakir Aharonov and David Bohm.
27. Barnett effect
The Barnett effect is the magnetization of an uncharged body when spun on its axis. It was discovered by American physicist Samuel Barnett in 1915.
28. Bezold–Brücke effect
The Bezold–Brücke shift is a change in hue perception as light intensity changes. As intensity increases, spectral colors shift more towards blue (if below 500 nm) or yellow (if above 500 nm). At lower intensities, the red/green axis dominates. This means that the Reds become Yellower with increasing brightness. Light may change in the perceived hue as its brightness changes, despite the fact that it retains a constant spectral composition. It was discovered by Wilhelm von Bezold and M.E. Brücke.
29. Catapult effect
In electromagnetics, the catapult effect is a phenomenon occurring when a current is passed through two wires connected by a loose wire in a magnetic field. The loose wire is then catapulted horizontally away from the magnetic field.
30. Greenhouse effect
The greenhouse effect is the process by which radiation from a planet's atmosphere warms the planet's surface to a temperature above what it would be without this atmosphere. When the Sun's energy reaches the Earth's atmosphere, some of it is reflected back to space and the rest is absorbed and re-radiated by greenhouse gases. The absorbed energy warms the atmosphere and the surface of the Earth.
31. Cheerios effect
It is the phenomenon that occurs when floating objects that do not normally float attract one another, or are attracted to the walls of the bowl. Objects that float at the interface between a liquid and a gas interact because of interfacial deformation and the effect of gravity. Wetting, an example of the "Cheerios effect," is when breakfast cereal clumps together or clings to the sides of a bowl of milk. It is named after the common breakfast cereal Cheerios and is due to surface tension. The same effect governs the behavior of bubbles on the surface of soft drinks.
32. Christofilos effect
Christofilos effect, sometimes known as the Argus effect, refers to the entrapment of electrons from nuclear weapons in the Earth's magnetic field. It was first predicted in 1957 by Nicholas Christofilos, who suggested the effect had defensive potential in a nuclear war, with so many beta particles becoming trapped that warheads flying through the region would experience huge electrical currents that would destroy their trigger electronics.
33. Hawking Effect
In the framework of quantum field theory in curved spacetimes, Stephen Hawking showed that quantum effects allow black holes to emit radiations in a thermal spectrum. This thermal radiation is with a temperature inverse to the black hole’s mass. Physical insight on the process may be gained by imagining that particle antiparticle radiation is emitted from just beyond the event horizon. This radiation does not come directly from the black hole itself, but rather is a result of virtual particles being "boosted" by the black hole's gravitation into becoming real particles. An observer falling into a black hole would not measure any particles and think the black hole is surrounded by vacuum. But an observer far away from the black hole would think the horizon is surrounded by particles.
34. Wilson–Bappu effect
A relationship between a property of the calcium K line in late-type stars and the luminosity of the star. When the strong calcium absorption line is observed at high resolution it is often found to have a weak emission at its centre. The strength of this line has been found to correlate with the star's brightness.
The effect is named after the American astronomer Olin Chaddock Wilson (1909–94) and the Indian astronomer M.K.Vainu Bappu (1927–82).
35. Sommerfield effect
Sommerfeld effect is a phenomenon arising from feedback in the energy exchange between vibrating systems: for example, when for the rocking table, under given conditions, energy transmitted to the motor resulted not in higher revolutions but in stronger vibrations of the table.
36. Quantum Zeno Effect
The Quantum Zeno Effect describes the slowing down of the evolution of a quantum system under repeated measurements. In the limit of arbitrarily dense measurements motion would be completely inhibited.
The name “quantum Zeno effect” (or “Zeno paradox”) was introduced by Misra and Sudarshan in 1977
37. Ground Effect
Ground Effect is the name given to the positive influence on the lifting characteristics of an aircraft wing when it is close to the ground. This effect is a consequence of the distortion of the airflow below wing surfaces attributable to the proximity of the ground. For fixed-wing aircraft, ground effect is the reduced aerodynamic drag that an aircraft's wings generate when they are close to a fixed surface. When landing, ground effect can give the pilot the feeling that the aircraft is "floating". When taking off, ground effect may temporarily reduce the stall speed.
38. Kerr Effect
The Kerr effect, also called the quadratic electro-optic (QEO) effect, is a change in the refractive index of a material in response to an applied electric field. All materials show Kerr effect, but certain liquids display it more strongly than others. The Kerr effect was discovered in 1875 by John Kerr, a Scottish physicist.
