Graham's law

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Related to Graham's law of effusion: Graham's Law of Diffusion

Graham's law

the rate of diffusion of a gas through porous membranes varies inversely with the square root of its density.

Graham's law

Etymology: Thomas Graham, English chemist, 1805-1869
the law stating that the rate of diffusion of a gas through a liquid (or the alveolar-capillary membrane) is directly proportional to its solubility coefficient and inversely proportional to the square root of its density.


1. A scientific statement that is found to apply to a class of natural occurrences.
2. A body of rules, regulations, and legal opinions of conduct and action that are made by controlling authority and are legally binding.

administrative law

Body of law in the form of decisions, rules, regulations, and orders created by administrative agencies under the direction of the executive branch of the government used to carry out the duties of such agencies. Regulations of nursing practice, for example, are considered administrative laws.

all-or-none law

The weakest stimulus capable of producing a response produces the maximum contraction of cardiac and skeletal muscle cells, and the maximal impulse transmission rate in neurons.

apology law

A colloquial term for any legal statute that encourages health care providers to acknowledge and disclose medical errors openly. Although apology laws vary from one jurisdiction to another, most include some measure of legal protection for the individual or agency making the apology.

Avogadro's law

See: Avogadro, Amedeo

Baruch's law

See: Baruch's law

Beer's law

See: Beer's law

Bell's law

See: Bell, Sir Charles

law of Bergonié and Tribondeau

A fundamental law of radiation biology that states that the radiosensitivity of a tissue is increased the greater the number of undifferentiated cells in the tissue, the greater the mitotic activity, and the greater the length of time that they are actively proliferating.

biogenetic law

Ontogeny recapitulates phylogeny, i.e., an individual in its development recapitulates stages in its evolutionary development. Synonym: Haeckel's l

Boyle's law

See: Boyle's law

case law

Opinions or decisions made by the courts.

Charles' law

See: Charles' law

common law

A system of law that originated in medieval England and is based on former legal decisions (precedent) and custom, not on legislation. Common law constantly evolves from previous decisions and changing custom. It forms the basis of the legal system in the U.S. (except Louisiana), the U.K. and most other English-speaking countries and is therefore the most frequent source of legal precedent for malpractice cases.

cosine law

1. A physical law that describes the relationship between the sides and angles of any triangle.
2. When applied to physical treatment of the body, it describes the effectiveness of radiant energy and the angle at which it strikes tissue. The maximum amount of energy transfer occurs when the energy strikes tissue at a 90° angle. As the angle changes, the effectiveness of the energy is reduced by the multiple of the cosine of the angle: Effective energy = applied energy × cosine of the angle.

law of contiguity

1. A law stating that if two ideas occur together, then the recollection of one will likely stimulate recall of the other.
2. A law stating that if combined stimuli precede contraction of a muscle, then, when those stimuli are repeated, the muscle will contract again.

Courvoisier's law

See: Courvoisier's law

criminal law

The area of the law relating to violations of statutes that pertain to public offenses or acts committed against the public. For example, a health care provider can be prosecuted for criminal acts such as assault and battery, fraud, and abuse.

Dalton's law

See: Dalton's law

law of definite proportions

Two or more elements when united to form a new substance do so in a constant and fixed proportion by weight.
See: Dalton's law

law of effect

The psychological principle that positively reinforced behaviors will be repeated and negatively reinforced behaviors will diminish or be extinguished.

Fechner's law

See: Fechner's law

Fick's law

See: Fick, Adolf Eugen

Frank-Starling law

See: Starling's law.

fraud and abuse law

A statute that regulates the appropriateness of health care provider behavior in billing practices, receipt of payments, and provision of medically necessary services.

Gay-Lussac's law

Charles' law.

Good Samaritan law

The legal protection given to those who stop and render care in an emergency situation without expectation for remuneration. The necessity for this legislation arose when physicians who assisted in giving emergency care were later accused of malpractice by the patient.

Graham's law

See: Graham's law

law of Grotthus-Draper

See: Grotthus-Draper, law of

Gudden's law

See: Gudden, Bernhard Alloys von

Haeckel's law

Biogenetic law.

law of the heart

Other things being equal, the stroke volume of the heart varies as the extent of diastolic filling, that is, the energy of contraction is a function of the initial length of the muscle fibers.

Hellin's law

See: Hellin's law

Henry's law

See: Henry's law

Hilton's law

See: Hilton, John

Hooke's law

See: Hooke's law

law of the intestine

Moderate distention of the intestine at a point causes relaxation below (aborally to the point) and contraction above.

inverse-square law

The intensity of radiation or light at any distance is inversely proportional to the square of the distance between the irradiated surface and a point source. Thus, a light with a certain intensity at a 4-ft distance will have only one-fourth that intensity at 8 ft and would be four times as intense at a 2-ft distance.

law of Laplace

See: law of Laplace

law of Magendie

Bell's law.

Marey's law

See: Marey's law

Mariotte's law

Boyle's law.

law of mass action

In any chemical reaction, the ratio of the mathematical products of the concentrations of the products (raised to the power of the chemical coefficients in the balanced equation) to the mathematical products of the concentrations of the reactants (similarly raised) is constant at a given temperature.

Mendel's laws

See: Mendel's laws

law of multiple proportions

When two substances unite to form a series of chemical compounds, the proportions in which they unite are simple multiples of one another or of one common proportion.
See: Dalton's law

Nysten's law

See: Nysten's law

Ohm's law

See: Ohm's law

periodic law

The physical and chemical properties of chemical elements are periodic functions of their atomic number. A natural classification of elements is made according to their atomic number. When arranged in order (through calcium, atomic number 20), elements show regular variations in most of their physical and chemical properties.

Poiseuille's law

See: Poiseuille's law

Q law

As temperature (in degrees Kelvin) decreases, chemical activity decreases.

law of reciprocal proportions

In chemistry, the proportions in which two elementary bodies unite with a third one are simple multiples or simple fractions of the proportions in which these two bodies unite with each other.

reciprocity law

Any milliamperage multiplied by an exposure time setting that gives the same milliamperage-second outcome should give the same relative density to an image. However, this law is dramatically affected by the image receptor response curve, esp. when it is not a 45° linear curve. In radiographic intensifying film and screen technologies, the reciprocity law does not hold at long exposure times because of the reversal of the D log E response curve.

right-to-know law

A law that dictates that employers must inform their employees of the health effects and chemical hazards of the toxic substances used in each workplace. The employer must provide information concerning the generic and chemical names of the substances used; the level at which the exposure is hazardous; the effects of exposure at hazardous levels; the symptoms of such effects; the potential for flammability, explosion, and reactivity of the substances; the appropriate emergency treatment; proper conditions for safe use and exposure to the substances; and procedures for cleanup of leaks and spills. The law provides that an employee may refuse to work with a toxic substance until he or she has received information concerning its potential for hazard.
See: hazardous material; health hazard; material safety data sheet; permissible exposure limits

Rubner's laws

See: Rubner's laws

Starling's law

See: Starling's law

Starling's law of intestine

See: Starling's law of intestine

Stoke's law

See: Stoke's law

Sutton's law

See: Sutton's law

van 't Hoff's law

See: van 't Hoff's law

Waller's law of degeneration

See: Waller's law of degeneration

Weber's law

See: Weber's law

Weigert law

See: Weigert, Carl

Wolff's law

See: Wolff's law

Graham's law

the rate of diffusion of a gas through porous membranes varies inversely with the square root of its density.