Прочитайте текст и выполните задания. Vacuum 1. Evangelista Torricelli produced the first laboratory...: ответ на тест 1045161 - Английский язык

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Vacuum
1. Evangelista Torricelli produced the first laboratory vacuum in 1643, and other experimental techniques were developed as a result of his theories of atmospheric pressure. A torricellian vacuum is created by filling a tall glass container closed at one end with mercury and then inverting the container into a bowl to contain the mercury.
2. The quality of a vacuum refers to how closely it approaches a perfect vacuum. Residual gas pressure is a primary indicator of quality, and is most commonly measured in units called torr, even in metric contexts. Lower pressures indicate higher quality, although other variables must also be taken into account.
3. Vacuum became a valuable industrial tool in the 20th century with the introduction of incandescent light bulbs and vacuum tubes, and a wide array of vacuum technology has since become available. The recent development of human spaceflight has raised interest in the impact of vacuum on human health, and on life forms in general.
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Vacuum
1. Evangelista Torricelli produced the first laboratory vacuum in 1643, and other experimental techniques were developed as a result of his theories of atmospheric pressure. A torricellian vacuum is created by filling a tall glass container closed at one end with mercury and then inverting the container into a bowl to contain the mercury.
2. The quality of a vacuum refers to how closely it approaches a perfect vacuum. Residual gas pressure is a primary indicator of quality, and is most commonly measured in units called torr, even in metric contexts. Lower pressures indicate higher quality, although other variables must also be taken into account.
3. Vacuum became a valuable industrial tool in the 20th century with the introduction of incandescent light bulbs and vacuum tubes, and a wide array of vacuum technology has since become available. The recent development of human spaceflight has raised interest in the impact of vacuum on human health, and on life forms in general.
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Electricity
1. Electricity is a flow of negative charges called electrons. These electric charges are measured in units called coulombs. Electricity is a very versatile form of energy that can be converted into many other forms of energy, including light and heat, direct current (DC), which flows in one direction only, and alternating current (AC), which changes direction 60 times per second.
2. An electric circuit is an unbroken conducting path from, and back to, a power supply. It has three main parts: the power supply, the conductor, and the load. The power is provided by a generator or battery, the conductor carries the current, and the load is an electric device such as a lamp.
3. Unlike current electricity, static electricity does not flow. It is created when an electrically neutral substance loses or gains electrons, making it, respectively, positively or negatively charged. You can create static electricity by rubbing a balloon on your clothing. Electrons will move from the clothing to the balloon, making the balloon negatively charged and the clothing positively charged. The resulting static electricity on each will attract small, light objects such as pieces of paper.
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Solid
1. Solid is one of the major states of matter. It is characterized by structural rigidity and resistance to changes of shape or volume. Unlike a liquid, a solid object does not flow to take on the shape of its container, nor does it expand to fill the entire volume available to it like a gas does. The atoms in a solid are tightly bound to each other, either in a regular geometric lattice or irregularly one.
2. The branch of physics that deals with solids is called solid-state physics, and is the main branch of condensed matter physics (which also includes liquids). Materials science is primarily concerned with the physical and chemical properties of solids. Solid-state chemistry is especially concerned with the synthesis of novel materials, as well as the science of identification and chemical composition.
3. The forces between the atoms in a solid can take a variety of forms. For example, a crystal of sodium chloride (common salt) is made up of ionic sodium and chlorine, which are held together by ionic bonds. In diamond or silicon, the atoms share electrons and form covalent bonds. In metals, electrons are shared in metallic bonding. Some solids, particularly most organic compounds, are held together with van der Waals forces resulting from the polarization of the electronic charge cloud on each molecule. The dissimilarities between the types of a solid result from the differences between their bonding.
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Electromagnetism
1. Electricity and magnetism combine to form one of the fundamental forces of the universe – electromagnetism. The two constantly interact, and the relationship between them is one of the most important in physics. For example, an electric current passing through a wire creates a magnetic field; and if the lines of force around a magnet are cut by a passing object, an electric current will be produced.
2. Magnets are attracted to iron and to any material that contains iron. Magnets have two poles, a north pole and a south pole. Unmagnetized iron and steel have magnetic regions of atoms called domains that are jumbled up and point in lots of different directions. When iron or steel becomes magnetized, the domains become aligned and they all point in the same direction. One end of each domain points toward the magnetic north pole.
3. Electronics is a new branch of physics, and one that plays an increasingly important part in our lives. It is concerned with the use of electricity to produce signals that carry information and control devices such as computers. These devices contain electric circuits through which electric current flows. The controlling parts in a circuit are called components, and these include diodes and transistors. Components can amplify currents, switch them on and off, or change their direction.
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Light
1. The form of energy that illuminates our world is called light. It usually comes from hot objects, like the sun or fire, but it is also produced by electricity and some chemical reactions. Light is the only part of the electromagnetic spectrum (which includes microwaves, ultraviolet rays, and X-rays) that is invisible to the human eye. It travels at 186,000 miles (300,000 km) per second, and nothing can travel faster. Like other forms of energy, light travels in waves, but it can also travel in packets of energy called quanta. This enables it to travel through a vacuum.
2. Light rays are reflected when they hit a shiny or silvered surface, such as a still pool of water or a mirror. Reflection involves two light rays: the incoming ray and the reflected ray which bounces off the reflecting surface. The two rays are at identical angles to the reflecting surface on either side of an imaginary line.
3. Refraction is a property of all types of energy that travel in waves, including light. Light waves normally travel in straight lines, but when they pass from one transparent material to another, they usually refract, or bend. Refraction occurs because light travels at different speeds in different materials. As light from a material with a low density, such as air, enters a material with a high density, such as water, its speed is reduced. This causes it to bend (except when it enters a material at a right angle).
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