energy have many common characteristics, the most fundamental of which concerns their nature. They are all wave motion, consisting of varying electric and magnetic fields, but they can also be considered as being made up of “particles,” or quanta, of energy called photons. Radiant energy therefore has a dual wave/particle nature. The most important forms of electromagnetic radiation are visible and infrared light for the life.
Another basic characteristic of electromagnetic radiation is the fact that it does not need a medium in which to travel, and so it can travel through vacuum of space. But the various forms of radiation can also travel through other mediums: light travels through air, water, and glass, for example, and even pass through metal; that is to say, even a metal is “transparent” to X-rays and gamma rays.
In a vacuum, all forms of electromagnetic radiation travel at the same constant velocity — called the speed of light. In other transparent mediums, they travel more slowly, the velocity depending on the wavelength of the radiation and, generally, on the density of the medium. In other mediums, different wavelengths travel at slightly different velocities. The longer the wavelength, the faster the radiation travels. So in the case of visible light, red light travels faster than blue light in any particular transparent medium does.
The various types of radiant energy have different wavelengths and frequencies. These two characteristics multiplied by the frequency are equal to the velocity. Because the velocity is constant in any particular medium, wavelength and frequency are inversely proportional to each other; the longer the wavelength, the lower the frequency is, and vice versa.
3.4. Найдите предложение, содержание которого не соответствует теме и смыслу текста.
1. Energy may take various forms — sound, chemical and electrical energy, for example.
2. The various forms of radiant energy have many common characteristics, the most fundamental of which concerns their nature.
3. Another basic characteristic of electromagnetic radiation is the fact that it does not need a medium in which to travel.
4. In a vacuum all forms of electromagnetic radiation travel at the same constant velocity.
5. You can buy an air conditioner which work without electricity.
3.5. Найдите перевод этих предложений в тексте.
1. Энергия может быть различных форм, например: звуковая, химическая электроэнергия и др.
2. Самыми важными формами электромагнитного излучения являются видимый свет и инфракрасное излучение для жизни
3. Различные формы энергии излучения имеют много общих свойств.
4. Теоретически возможно объяснить все свойства энергии излучения с помощью понятий «волновое движение» и «фотон».
5. Волновое движение — это одна из форм радиоактивной энергии.
6. Различные формы излучения могут проходить через другую среду.
7. Свет проходит через воздух, воду, стекло.
8. Даже металл «прозрачен» для Рентгеновских и гамма лучей.
3.6. Переведите выражения из текста на русский язык
1. various forms of radiation _______________________________________
2. wavelengths and frequencies ____________________________________
3. the same constant velocity ______________________________________
4. infrared and visible light ________________________________________
5. common characteristics _________________________________________
6. particular medium _____________________________________________
7. the speed of light _______________________________________________
8. density of the medium __________________________________________
3.7. Вставьте пропущенные слова. Используйте подсказку:
1. The various types of radiant energy have different wavelengths and f________.
2. The most important form of electromagnetic radiation is v________ light.
3. The most fundamental radiant energy characteristics d________ on their nature.
4. Various forms of radiation can also travel through other m________.
5. All forms of electromagnetic radiation travel at the same constant v________.
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