1. Peter wants to become a - superstar a. legend

b.global
c rhythm
d. guest
2. My mother grew
in Mexico City.
a. up
b. on
c. in
d. out
3. Mark
in a local song competition and came second.
a. entertained
b. protested
C. competed
d. mixed
4. Justin Bieber recorded his
album My World 20 in 2010.
a. debut
b. period
c. brief
d. lyrics
5. The music business is very
a. appealing b. competitive c. completed d. compulsory
5. Angela has proved her talent and over again.
a. under
b. across
c. again
d. over
He has won many awards. actual fact, he's won more than twenty awards.
a. For
b. To
c. In
d. At

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