Дополните диалог:
Teacher: Hello, my friends. Today, I’m going to show you an operating 1_______.
Ivan: That’s great! By the way, what does the word “laser” mean?
Teacher: 2_______. Looking at the operating laser one can see it producing a very powerful beam of light.
Ivan: When did the first lasers appear, I wonder?
Teacher: As far as I know, in the 1960s. Yet, we hear of their having numerous applications. 3_______.
Ivan: And how do lasers work?
Teacher: Their work is based on the principle of amplifying the light of a certain wavelength in the resonator cavity.
Ivan: I’m rather interested in making experiments with laser beams.
Teacher: Then let’s try to make one. But be very careful. Lasers can be very 4_______.
Ivan: Why are they dangerous?
Teacher: Well, they produce a very powerful beam of light and if treated in the wrong way it can hurt or even kill you.
Ivan: Oh, I’m pretty scared.
Teacher: Don’t worry. If you follow all the safety instructions nothing will happen to you.
laser
It denotes light amplification by stimulation of emission of radiation
Industrial welding, cutting materials, making measurements, etc. will be practically impossible without this device
dangerous
