It was Newton who formulated the basic concept that light from ordinary sources is complex. By "complex" he meant that such light could be analysed into colours and the colours could be used to synthesize light.
How does laser light differ from ordinary light? In brief, it is much more intense, directional, monochromatic and coherent.
We know the light emitted by an ordinary source such as candle or an incandescent lamp to consist of uncoordinated waves of many different lengths, that is, it is incoherent and more or less white.
The scientists found the waves of laser light to be coordinated in space and time and to have nearly the same length. This coherence and chromatic purity and also intensity of laser light result from the fact that in a laser excited atoms are stimulated to radiate light before they have had time to do so spontaneously and independently. The directionality of laser light arises from the geometry of the laser. These properties of laser light suggest many uses for it both in technology and in physics. The scientists consider laser light to be different from ordinary light even when it merely illuminates a surface. The surface looks grainy and sparkles.
By means of some instruments it has become possible to examine materials and physical phenomena in new ways. Among the most interesting applications of the laser the probing of materials by the study of their scattering of light should be mentioned.
The laser is being applied to probe the internal structure and behaviour of molecules by examining the light-scattering phenomena. Many investigators are working at the development of coherent light sources, those ones whose wave-length can be changed. Many amplifiers and oscillators have been constructed for this purpose lately.
Laser light is applied in many fields such as medicine, biology, industry and so on. We can say scientists made laser light serve man.
The scientists found the energy density of the image formed by a lense in a laser beam to be used to heat, melt or even vaporize small areas of any material. Laser is also used to pierce holes in diamond.
Nowadays laser can be used to cut a wide range of materials including wood and paper.
Объяснение: ответ может быть не правильный
Read the text and do the task below.
Look at the e-mail. Your friend Chris has just moved to England. He has sent you a letter about his new school.
Dear friend!
I'm fine and hope the same for you. I'm writing this letter telling you about my first day at the new school.
My new school is very big. It has four floors, a lot of stairs, big dassrooms and huge lunch room where you get to pick your own lunch. It has a park across the street called Douglas and a playground in the back and you can go to the park or the playground at the break.
My classroom is on the second floor. It's light and clean. There are three large windows in my classroom. On the walls of our dassroom there are different colour maps, portraits and posters.
There are many opportunities to go in for sports in our school. Our school has a gym, a sports ground, a
football field, a swimming pool and other sports facilities.
However I'm feeling very unhappy. Because, I haven't got any friends here. I tried very hard to make
friends at school, but people don't like to talk to me.
Can you tell something about the ways I can make friends? Please, give me some advice.
Love, Chris.
Mark sentences True or False.
1. Chris's school is very big. It has five floors. [ 1 ]
2. It has a playground in the back. [ 1 ]
3. His classroom is on the second floor. [ 1 ]
True
false
true
Объяснение: