photoelectric effect


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effect

 [ĕ-fekt´]
a result produced by an action.
additive effect the combined effect produced by the action of two or more agents, being equal to the sum of their separate effects.
adverse effect a symptom produced by a drug or therapy that is injurious to the patient.
Bainbridge effect Bainbridge reflex.
Bohr effect decreased affinity of hemoglobin for oxygen caused by an increase of carbon dioxide; the oxyhemoglobin dissociation curve is displaced to the right because of higher partial pressure of carbon dioxide and lower pH. See also Haldane effect.
The Bohr effect causing a shift to the right in the oxyhemoglobin dissociation curve.
Crabtree effect the inhibition of oxygen consumption on the addition of glucose to tissues or microorganisms having a high rate of aerobic glycolysis; the converse of the Pasteur effect.
cumulative effect the action of a drug or treatment resulting from repeated use.
Doppler effect see doppler effect.
experimenter e's demand characteristics.
extrapyramidal e's the side effects caused by neuroleptic medications, including dystonias, parkinsonism, akathisia, and tardive dyskinesia.
Haldane effect increased oxygenation of hemoglobin promotes dissociation of carbon dioxide; see also Bohr effect.
Hawthorne effect a psychological response in which the subjects in a research study change their behavior simply because they are subjects in a study, not because of the research treatment.
heel effect variation in x-ray beam intensity and projected focal spot size along the long axis of the x-ray tube from cathode to anode.
parallax effect the position of the image on each emulsion of dual emulsion film; it is accentuated by tube-angled x-ray techniques.
Pasteur effect the decrease in the rate of glycolysis and the suppression of lactate accumulation by tissues or microorganisms in the presence of oxygen.
photoelectric effect ejection of electrons from matter as a result of interaction with photons from high frequency electromagnetic radiation, such as x-rays; the ejected electrons may be energetic enough to ionize multiple additional atoms.
placebo effect the total of all nonspecific effects, both good and adverse, of treatment; it refers primarily to psychological and psychophysiological effects associated with the caregiver-patient relationship and the patient's expectations and apprehensions concerning the treatment. See also placebo.
position effect in genetics, the changed effect produced by alteration of the relative positions of various genes on the chromosomes.
pressure effect the sum of the changes that are due to obstruction of tissue drainage by pressure.
proarrhythmic effect any new, more advanced form of arrhythmia caused by an antiarrhythmic agent, especially those that produce hemodynamically important symptoms. These arrhythmias occur less than 30 days after initiation of treatment and are not due to a new event such as acute myocardial infarction or hypokalemia.
side effect a consequence other than that for which an agent is used, especially an adverse effect on another organ system.
Somogyi effect see somogyi effect.

pho·to·e·lec·tric ef·fect

1. the loss of electrons from the surface of a metal on exposure to light;
2. a mode of interaction of radiation with matter in which all of the energy of the incident photon is absorbed, with ejection of a photoelectron and characteristic radiation from filling the vacancy from another shell; since the energy absorption per gram of tissue is proportional to the cube of the atomic number, this mode is important in diagnostic radiography.

photoelectric effect

Radiology That fractional ↓ in beam intensity of ionizing radiation due to photoelectric effect in a medium through which it passes. See Attenuation coefficient.

pho·to·e·lec·tric effect

(fōtō-ĕ-lektrik ĕ-fekt)
The interaction of an incoming photon with the inner shell electron of an atom that causes the electron to be ejected, resulting in a photoelectron.
References in periodicals archive ?
It was concluded that this is a consequence of the dominant influence of photoelectric effect in X-ray cases in comparison to Compton's effect in gamma-ray cases.
By then, brother Maurice had a well-furnished laboratory in Paris, where he was conducting experiments on the photoelectric effect, using X rays.
The anisotropic photoelectric effect was systematically investigated along the tilted direction and untilted direction.
There may be other causes of this behavior, such as the photoelectric effect producing static electricity, chemical-bonding forces, magnetism, or vacuum welding at macroscopic distances.
Einstein in his career as a scientist developed the special and general theories of relativity and won the Nobel Prize for Physics in 1921 for his explanation of the photoelectric effect. Recognized in his own time as one of the most creative intellects in human history, Einstein in the first 15 years of the 20th century advanced a series of theories that proposed entirely new ways of thinking about space, time, and gravitation.
Now that electrons were known, the photoelectric effect could be studied more effectively.
- Part 8: Delivery of educational kits to the visualization of elementary particles - Foggy chamber, measuring an electric charge, the study of cathode rays and thermionic emission, the photoelectric effect,
Photoelectric effect, Compton scattering, and pair production eject electrons from the atoms of the material.
By shining an ultraviolet light on the surface of the liquid metal, they produced a photoelectric effect that prevented the separation of charges between the two materials.
With the discovery of the electron and its emission from many different metals by way of the photoelectric effect, there was no use in continuing to pretend that the atom was a featureless, indivisible particle.
345X385x170mm And 3 Kg, It Should Be Compact In Size, Novel In Design And Lcd Display And Should Be Based On Principle Of Photoelectric Effect, It Should Be Able To Measure The Whitness Index Of Railway Supplied Linnes In Ac Coaches.
In 1905 the photoelectric effect, as observed by Lenard (see 1902), was combined with quantum theory (see 1900) by Einstein.

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