Which one of the following statements is incorrect about laser?
1.It is a technique for producing intense beams of light, ultraviolet or infrared radiation of different wavelength.
2.Even in diamond laser beam can drill a hole.
3.A variety of lasers have been made from solids like the ruby crystal and semi conducting materials, liquids and gases.
4.All waves in laser, travel in phase.
Posted Date:-2021-03-06 14:09:03