Who was Hans Christian Oersted?

  Hans Christian Oersted was the Danish physicist and chemist who founded the branch of science called electromagnetism. Electromagnetism deals with magnetic fields developed by electricity.
  During an evening lecture at the University of Copenhagen where Oersted served as professor, he accidentally discovered that a magnetic needle was deflected by an electrical current. This discovery established him as one of the outstanding physicists of his age. After experimenting, Oersted discov­ered that every conductor which carries an electrical current is surrounded by a magnetic field. This experiment, now known as the "Oersted Experiment," proved that electricity can produce magnetism. In 1934 the "Oersted" was adopted as the unit of
measurement of the strength of a magnetic field.

How does a Geiger counter work?

The Geiger counter is a device used to know how much radioactivity is present in a substance or in a finished area. The counter works in a similar way to a neon light.

In a neon light, an electric current excites the gas molecules inside the crystal tube, making them shine brightly. Like neon light, a Geiger counter consists of a gas tube, with two pieces of metal inside it. The radiation consists of particles traveling at high speeds and energy waves, and together, excite the gas molecules inside the counter tube as they pass through it.

The molecules of the excited gas establish an electric current between the two pieces of metal inside the tube. The metal is attached to an amplifier and a meter, which increase and read the current. The strength of the current indicates the level of radiation. Also, depending on the force of the electric current is the volume of sound that the counter makes when it finds radioactivity.

Since a Geiger counter reads only radioactivity, it cannot be used to find metals such as silver or gold, which are not radioactive. However, it can be used to find uranium.

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What is fire made of?

 Fire is a chemical reaction resulting from the combination of a fuel with atmospheric oxygen. Once initiated, this reaction is self-sustaining, generates high temperatures and produces heat, light, gases and particulate matter.

The visible region of the flame is where this chemical process takes place, i.e. fire is essentially a phase of the gaseous phenomenon: For combustion to take place, solid and liquid fuels must become gases.

By boiling a liquid, this transformation is achieved; the solids reach it through a process called pyrolysis, which generates volatile gases.

The flame itself is a plasma of very hot atoms that emit energy in the form of light while its electrons, which have reached higher energy levels by absolving heat, fall into lower energy states.

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What is Universal Time?

Pope Gregory XIII

The Gregorian calendar we use in the western world is closely related to the Earth's orbit around the Sun.

The effort to unify all measures of time has led to the establishment of a "universal time" according to which all the official clocks of the world that are governed by our system are adjusted.

That time is the result of the measurements of powerful atomic clocks that are only wrong one second for every million years.

The responsibility for their care and adjustment lies with the Office of Weights and Measures of Sèvres in France. Another factor in weighting the exact time is the measurement of the displacement of the planet that is carried out at the International Service for Earth Rotation Measurements in Paris.

A FACT

Did Cervantes and Shakespeare die on the same date?

Cervantes died, officially, on April 23, 1616... of the Gregorian calendar, which was already in force in Spain. And Shakespeare also did so, in effect, on April 23... but from the Julian calendar (May 3 in the Gregorian calendar), still in force in England.

In other words, they actually died 10 days apart.

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How does an earthquake happen?

An earthquake is a sudden shake of the earth's crust that occurs unexpectedly. The earthquake, has its origin in a point inside the Earth called a hypocentre or focus, which is normally located less than 50 km deep, because if it is below that level, the earthquake does not usually reflect on the outside.

The point corresponding to the perpendicular of the hypocentre on the surface is the epicentre, where the earthquake registers its maximum intensity. The hypocentre generates waves, the seismic waves, which propagate on the surface, losing intensity as they move away from the epicentre.

The magnitude of an earthquake values the amount of energy released in the focus at the time it occurs. To measure the magnitude of earthquakes is used a scale of ten degrees developed by the American seismologist C. F. Richter. The intensity of an earthquake is based on the evaluation of the effects produced by seismic waves in the affected area. The intensity was measured using a twelve-degree scale created by the Italian G. Mercalli, which was slightly modified in 1964. These and other important characteristics of earthquakes (amplitude, duration, time, etc.) are reflected in the seismograph, which is a device that records seismic waves.

seismograph

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What are gamma rays?

With the help of a satellite and a global network of telescopes, astronomers can see and locate stellar explosions at a very long distance. A gamma-ray burst is an event caused by a star that died in one of the early stages of the universe.

The record of light that generates explosions of this type serves researchers to collect data on the evolution of the cosmos, ''its intensity exceeds that of galaxies in brightness; it releases an enormous amount of gamma rays and particles that travel at the speed of light,'' says Donald Lamb, an astrophysics expert at the University of Chicago.

The challenge faced by astronomers in the face of this phenomenon is that the gamma ray shots that produce light last only seconds before dissipating. To locate them, NASA launched the Swift satellite, which has a gamma-ray telescope that locates them in fractions of a second and sends their coordinates by e-mail to almost a thousand astronomers around the world.

The light from the bursts comes from stars that exploded when the universe was just a few hundred million years old. A gamma-ray burst offers a rare glimpse through space and time," says Nial Tanvir, an astronomer at the University of Hertfordshire, England.

George Ricker, an astronomer at the Massachusetts Institute of Technology, says: "If we can locate such ancient explosions, we may finally go back in time to know the origin and constitution of the first stars before galaxies existed.

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How safe is anesthesia?

Never has anesthesia been safer than today. There are three basic types of anesthesia: general anesthesia causes loss of sensation in the whole body, regional anesthesia causes loss of sensation in only one area, and local anesthesia causes loss of sensation in only one very specific area.

There are certain substances used in the anaesthetic process, such as nitrous oxide, whose frequent, excessive or prolonged use is linked to damage to the marrow and the nervous system, as it interferes with the action of vitamin B12.

In the past, cocaine was used as an anaesthetic, although it caused side effects such as addiction and overstimulation of the nervous system. The general anesthesia used today is contraindicated in specific cases of heart disease, use of certain drugs, certain neurology and other pre-existing medical conditions.

There are several levels in its effects or repercussions on the organism. The first consideration is the psychological aspect, since for adults, and especially for children, the anesthetic procedure -- preparation, application and recovery -- involves discomfort, anxiety and even physical pain. Being completely unconscious and in the hands of another person also causes a lot of stress, so that every time it is applied our organism suffers physiological, mental and emotional trauma.

From the medical point of view, the substances used tend to be eliminated from the body relatively quickly. In principle, anaesthesia is not harmful, but it is a field in which more effective substances are constantly discovered and the methods of application and monitoring are renewed.

The techniques used are safe, but their long-term effects have not yet been fully studied. On the other hand, if the patient suffers from any pre-existing illness or medical condition, it is vital to talk to the doctor before undergoing this procedure.

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How does a barometer work?

aneroid barometer

The air also has its weight, and like all other bodies exerts a pressure, by the effect of gravity, on the earth's surface. Many scientists came up with the idea of measuring this pressure, but the first to do so was Galileo Galilei, using a very long tube closed at one end. He filled it completely with water, and put the open end into a container full of water: the liquid in the tube descended, stopping at a height of ten meters. Some years later, Evangelista Torricelli, Galileo's pupil, wanted to repeat the experiment with a liquid much heavier than water, that is, with mercury. The mercury rose through the tube up to 76 centimetres. The new device was called a barometer (in Greek, baros means weight and metron means measurement). Torriceli soon realized that the column varied in height according to pressure variations. More modern is the aneroid barometer (a = no; neros = liquid), consisting of a steel box in which a vacuum has been made: the external pressure displaces one of its faces inwards or outwards, acting on a hand that indicates the displacements in a graduated sphere, thus indicating the variations in pressure and its intensity. This type of barometer, also known as a metallic barometer, is less cumbersome, although it is also less accurate than mercury. In addition, before being used, it has to be adjusted with a mercury barometer.

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Facts about Stephen Hawking

 It was in Oxford, England where Stephen Hawking was born on January 8, 1942.

Hawking was born on exactly the same day as the 300th anniversary of Galileo Galilei's death (8 January 1642).

Hawking published in 1988 A Brief History of Time, a bestseller in which he explained in clear language his cosmological theories.

Hawking's research shows that black holes lose mass over time, and eventually evaporate completely.

Stephen Hawking has suffered from amyotrophic lateral sclerosis since the early 1960s. Although the scientist can no longer speak and barely moves, his brilliant mind remains intact.

Hawking's current goal is unified field theory, which if successful, could finally combine quantum mechanics with relativity.

After Einstein, Stephen Hawking has been the most famous scientist of our era.

Hawking was the only person who played herself in the Star Trek television series.
On 14 March 2018, at the age of 76, he died at his home in Cambridge, United Kingdom.

Stephen Hawking died at his home in Cambridge, England, on 14 March 2018, at the age of 76

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Which element is most abundant in the universe?

75% of the matter in the universe is hydrogen.

The most abundant is hydrogen, a chemical element represented by the symbol H and with an atomic number of 1. Under normal conditions of pressure and temperature hydrogen is an odourless, colourless, tasteless, non-metallic and highly flammable diatomic gas (H2). With an atomic mass of 1.00794(7) u, hydrogen is the lightest chemical element and is also, as noted at the beginning, the most abundant element, constituting about 75% of the matter in the universe, mainly in stars and interstellar clouds.



SOME FACTS ABOUT HYDROGEN, THE MOST ABUNDANT ELEMENT IN THE UNIVERSE

Atomic number (number of protons in the nucleus): 1
Atomic symbol (in the Periodic Table of Elements): H
Atomic weight (mean mass of the atom): 1.00794
Density: 0.00008988 grams per cubic centimeter
Phase at room temperature: Gas
Melting point: minus minus 259.34 degrees Celsius
Boiling point: minus 252.87 C
Number of isotopes (atoms of the same element with a different number of neutrons): 3 common isotopes, of which 2 are stable.
Most common isotope: 1H, natural abundance 99.9885 percent.

What is Physiology?

Claude Bernard, the father of Physiology

     Physiology is the study of how living structures work. For example, in order to keep alive, all living things get ENERGY from food. They grow and reproduce new living forms just like themselves. They react to the world around them, and try to adjust to changes. As plant and animal life becomes larger and more complicated, the different parts of a body must be coordinated so they work together. Physiology studies these processes.
   Because the scientist must first understand how a thing is made, before he can understand how it works, a physiologist studies the various parts of the living structure—its ANATOMY. He studies the functioning of the structure. He may study how an individual NERVE CELL sends an impulse, how the muscles of the body move together, or why a plant produces flowers at certain times of the year.
But to have an understanding of the building materials of living things and the natural laws governing them, a physiologist must also know the basic PHYSICS and CHEMISTRY of the non-living world, as well as the biophysics and biochemistry of living structures.
   For example a boy or girl eats food and grows bigger. The physiologist checks digestion, circulation, elimination, metabolism, respiration, and excretion to find out what is happening to the food inside the person's body.

Which is the most active element?

   Fluorine is the most active of all the elements, and it reacts with nearly all other chemical elements. It is a greenish-yellow gas that is poisonous and very corrosive, and it has an irritating odor similar to that of chlorine. Fluorine belongs to the halogen group of elements. It has the smallest atoms and forms the strongest chemical bonds of all the halogens. Because of its great chemical activity, fluorine is very difficult to handle, and it must always be kept in a sealed, moisture-free container to prevent an explosive reaction with moisture. Many metals and other materials, such as wood and asbestos, spontaneously ignite and burn when they are placed in fluorine.
   The compounds of fluorine are called fluorides, and many are useful to man. For example, hydrogen fluoride, a colorless gas with an irritating odor, is used to etch glass, and sodium fluoride is used as an insecticide. To prevent enamel decay in teeth, many dentists apply fluorides to the teeth; many communities add fluorine compounds to their drinking water.
   Fluorine is commercially produced by the electrolysis of mixtures of hydrogen fluoride, HF, and molten potassium fluoride,

What is a gene?

   A gene is one of the units that determine the characteristics an organism inherits from its ancestors. Such inherited characteristics include height and the color of the skin, eyes, and hair. Some traits, such as a person's ability to curl his tongue, are determined by a single gene, and others, such as skin color, are determined by a combination of genes.
   Every cell has thousands of genes. They are located on the chromosomes, which are small thread like structures in the nucleus, and each gene occupies a specific place on a chromosome. The number of genes and the way in which they are arranged on the chromosomes are always the same in every member of a species.
   Since chromosomes usually occur in pairs, genes also are paired. The genes that have a similar location on each chromosome in a pair are called alleles. Alleles influence the same hereditary trait, but they may have a different effect on it. For example, the gene that produces short plants is an allele of the gene that produces tall plants. Each time a cell divides, every one of its genes makes a copy of itself. Occasionally a gene is changed in some way so that it has a different effect on a trait. Such a change in a gene is called a mutation. The original gene and the altered gene are alleles.
   Genes are too tiny to be seen, but biochemical studies have shown that they consist of nucleic acids combined with protein. It is believed that they exert their influence through the enzymes in cells. Each gene probably controls the synthesis of a specific protein. The protein, in turn, acts as an enzyme that makes possible a particular reaction in the cell. The reaction may be concerned with protein synthesis, growth, pigment formation, or any other activity in the cell.

What is Geometry?

   Geometry is the branch of mathematics concerned with the properties and relationships of points, lines, surfaces, solids, and angles. Geometry may be thought of as the science of space. Indeed, just as arithmetic is used to deal with experiences involving the counting process, so geometry is used to describe and relate experiences that involve space.
   The fundamental ideas of geometry are suggested by everyday experiences. Thus, the experience of where an object is leads to the idea of an exact, fixed location. This is the intuitive idea to which the term "point" refers. Many physical objects suggest the idea of a point. Examples include the corner of a block, the tip of a pencil, or a dot on a sheet of paper. Such things are called models or representations or pictures of points, although they show only approximately the idea in mind. Similarly, the set of points suggested by a tightly stretched string, the edge of a desk, or a flagpole is called a line segment. The physical objects that suggest line segments are called models, or representations, of segments. If a segment is extended indefinitely in one direction, it is called a ray, and if extended indefinitely in both directions, it is called a line. Similarly, the word "plane" is used to describe a flat surface like a floor, desktop, or chalkboard, but it is imagined as extending indefinitely in all directions. This means that a plane has no edges just as a line has no ends.
   The study of geometric figures that lie in one plane is often called plane geometry. The study of figures not all in one plane may be called solid geometry. Frequently, however, no distinction is made, and plane geometry and solid geometry are studied together as parts of the same course.

What is the fourth dimension?

 The fourth dimension is a concept used in mathematics and physics. Ordinary physical space seems to have just three dimensions; that is, every point in space can be located by giving just three numbers. However, mathematicians deal with abstract spaces that have any number of dimensions, from one to infinity. Each dimension can be used to represent a variable quantity. If a problem involves more than three variables, it can be considered in terms of a space of more than three dimensions.

Time as the Fourth Dimension. Physics deals with events that occur in space and time. Each event occurs at a certain location in space and at a certain point in time. The location in space can be defined by three physical coordinates, which correspond to the three spatial dimensions, or variables. The point in time can also be defined by a coordinate. In this sense, time is the fourth dimension, or fourth variable, of physics.
Galileo was the first mathematician to think of time geometrically. By using line segments to represent time intervals, he was able to use geometric proofs in physics. Time as a fourth dimension takes on a special importance in Einstein's theory of relativity. In this theory, space and time cannot be separately considered but must be thought of as a single four-dimensional entity. This entity is called space-time, or the space-time continuum.

What is Genetics?

   GENETICS is the biological science that deals with inheritance and variation among living organisms. In the reproduction of plants and animals it is obvious, even to the casual observer, that parents and offspring tend to resemble each other in many respects. For example, when a particular species of plant reproduces, it gives rise to other plants with the same general characteristics; the same holds true for the various species of animals. Even in human beings certain traits can be traced through families. This transmission of traits from one generation to another, and consequently the resemblance between closely related organisms, is called heredity.
   Although there may be many hereditary resemblances between individuals, no two individuals are ever exactly alike. All organisms, particularly higher animals, show some differences or variations. These may be due to the definite manner in which traits are distributed to the offspring, to environmental factors, such as temperature, light, moisture, food supply, etc., or to many other causes. Genetics, then, is that branch of the biological sciences that is concerned with the mechanisms of heredity and variation and with the relationship between the two phenomena.

What is a Gas?

   GAS is a substance which in physical properties is similar to AIR. Gases show little or no cohesive force and may be thus differentiated from liquids and solids. Heating any substance reduces the cohesive force, and theoretically, it is possible to change any substance to a gas by bringing it to a sufficiently high temperature. In general usage the term, gas, is limited to those substances which have the gaseous form under usual conditions of temperature and pressure. The prime physical characteristic of a gas is that it uniformly fills any vessel in which it is placed regardless of the vessel's shape or size. Liquids conform to the shape of the vessel only so far as they can fill it, and are bounded at the top by a liquid surface. The shape of solids is independent of that of the container.

Electron microscope

   The electron microscope is an instrument which permits scientists to see and photograph objects too small to be seen with an optical MICROSCOPE. The electron microscope uses beams of electrons in place of beams of light. Its magnifying power is about 200 times that of the very best optical microscope.
   The human eye is a very fine OPTICAL INSTRUMENT. However, the eye cannot distinguish objects smaller than about four one-thousandths of an inch.
   The power of an instrument to enlarge and form a distinct image of small details is its resolving power. The limit of resolution of an optical instrument is the smallest distance between two objects for which the instrument can form two distinct images of these objects.
   The magnifying power of an optical microscope is thus limited by the fact that objects cannot be distinguished unless they are somewhat larger than the waves of light reflected from them.
   In 1932 Ruska, a German, constructed an electron microscope. He allowed a beam of electrons to be reflected from an object. (Since electrons are charged they can be controlled by electric and magnetic fields.) The reflected electrons were directed through a magnetic field and then focused on a screen (as electrons are focused on a television screen to make a visible image) or on a photographic plate so that the image would be recorded.
   The superiority of the electron microscope over the optical microscope depends on the fact that fast-moving electrons have a wave length a thousand times smaller than the wave length of visible light.
   In most cases an electron microscope must be used with objects which are very thin. Thus, stray electrons will pass through them rather easily. Only recently has it been possible to investigate living matter with an electron microscope.
   The electron microscope can be used to investigate a wide variety of materials. Many applications have been made in chemistry, biology, metallurgy and other fields. Many new structures have been discovered in insects. Details which occur in chemical changes have been seen.

Neptunium

   Neptunium is an element that was found to be created during nuclear test explosions in World War II. It was the first man-made transuranium (following uranium) element.
   Neptunium (symbol Np) has more than 92 protons in its nucleus. It is element number 93 and the mass number of its most stable isotope is 237.
   The transuranium elements were prepared by the bombardment of the nuclei of uranium or more complex elements with neutrons and alpha particles. When uranium is bombarded with the neutrons, a new element is produced, neptunium. Np is unstable and forms still another man-made element, PLUTONIUM, which is also unstable.

What is diffusion?

   Diffusion is the redistribution of substances by the random motion of their molecules. Substances diffuse from regions where their concentration is high to regions where it is lower. The greater the difference in concentration, the faster the diffusion takes place.
   The action of diffusion is in apparent contradiction to the laws of gravity. When a gas is allowed to enter the bottom of a vessel that already contains a lighter gas, the heavy gas diffuses upwards and the lighter gas diffuses downwards until the two are uniformly mixed. The light gas molecules diffuse more rapidly than the heavier ones under the same conditions.
   Diffusion also takes place in liquids that can mix with each other. When separate layers of two such liquids are brought into contact, they diffuse into each other even when the denser liquid is in the lower layer. Solids diffuse into liquids in which they are soluble. Some solids also diffuse into other solids with which they are in contact. An example of this is the diffusion of gold into lead.
   In living organisms, diffusion is a very important natural process. In the human body, for example, oxygen diffuses from the lungs into the bloodstream, where its concentration is lower, and is carried to the body's tissues. At the same time, carbon dioxide, which is more concentrated in the blood, diffuses into the lungs and is exhaled.
   The term "diffusion" is also used to describe the process by which light is scattered when it passes through fog or frosted glass, or when it is reflected from a rough surface.