Прочитайте текст и выполните задания.
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).
Перед Вами конверт.
Соотнесите информацию под определенным номером на конверте с тем, что она обозначает.
All our _______ receive four weeks paid holiday per year.
Lady of the Snows is another name for …
He speaks French like a Frenchman, he _________ by an excellent teacher.
Прочитайте текст и выполните задания.
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.
Перед Вами конверт.
Соотнесите информацию под определенным номером на конверте с тем, что она обозначает.
Прочитайте текст и выполните задания.
Nuclear physics
1. The study of the nucleus of an atom is known as nuclear physics. As a result of this study, scientists have discovered ways of splitting the nucleus to release huge amounts of energy. There are two types of nuclear reactions: nuclear fission and nuclear fusion. A controlled nuclear reaction inside a power station can be used to provide heat and light for our homes.
2. Nuclear power stations use fission to produce their energy. Fast-moving atomic particles called neutrons are fired at the nucleus of an atom to split it. This splitting is called fission and it causes other atoms to split in a chain reaction. Some mass (the number of heavy particles inside an atom) is lost in the process. This is converted into large amounts of nuclear energy.
3. Nuclear fusion is a type of nuclear reaction that creates huge amounts of energy. It takes place naturally inside the sun, creating the heat energy that we need to survive on Earth. At temperatures of about 14 million C dgr. the nuclei of two hydrogen atoms fuse, or join together. In the process, some mass (the number of heavy particles inside an atom) is lost and converted into energy. Scientists are trying to develop this form of nuclear reaction as a safer alternative to the nuclear fission that takes place in power stations.
It was very stupid ________ him to make such a silly mistake.
Mary ________ use the dictionary when she reads Spanish books. She knows Spanish very well.