Практическое занятие 13

СКОРОСТЬ СВЕТА

THE SPEED OF LIGHT

Теоретическая часть

Данный лексический материал предназначен для знакомства и овладения общенаучными терминами, активному использованию предлагаемых слов и словосочетаний, подготовки к чтению, переводу и обсуждению общенаучных текстов.

to arrive прибывать

causality причинность, причинная связь

conversion трансформирование, переход

crucial решающий

instantaneous мгновенный

purpose цель

translucent просвечивающий, полупрозрачный

transparent прозрачный

wave волна

refractive преломляющий

Задания

Задание 1. Прочитайте и переведите текст.

The speed of light

The speed of light in the vacuum of free space is an important physical constant usually denoted by the symbol c₀ or simply c. The metre is defined such that the speed of light in a vacuum is exactly 299,792,458 metres per second.

The speed of light is of fundamental importance in physics. It is the speed of not just visible light, but of all electromagnetic radiation, as well as gravitation waves and anything having zero rest mass. In Einstein’s theory of relativity the speed of light plays the crucial role of a conversion factor between space and time within space time. This theory together with the principle of causality requires that no matter or information can travel faster than the speed of light.

The speed of light is so great that for many purposes it can be regarded as instantaneous. However, where long distances or accurate time measurements are involved, the finite speed of light can be important. For example, in the Global Positioning System (GPS), a GPS receiver measures its distance to satellites based on how long it takes for a radio signal to arrive from the satellite. In astronomy, distances are often measured in light-years, the distance light travels in a year (around ten trillion kilometers).

The speed of light when it passes through a transparent or translucent material medium, like glass or air, is less than its speed in a vacuum. The speed is described by the refractive index of the medium. In specially-prepared media, the speed can be tiny or even zero.

Задание2. Ответьте на вопросы:

1. What role does the speed of light play in Einstein’s theory of relativity?

2. Can it be regarded as instantaneous?

3. How are distances measured in astronomy?

4. Can the speed be tiny, or even zero?

5. Can the finite speed of light be important?

Вопросы к практическому занятию

1. Можете ли вы сказать, о чем текст, основываясь на заголовке?

Выскажите предположения.

2. К какому стилю литературы относится предлагаемый текст? Обоснуйте свой выбор.

3. Изложите основное содержание текста.