Question

Which of the following is not the main characteristic of laser beam?

• A. Highly intense
• B. Highly directional
• C. Highly monochromatic
• D. incoherent

Answer 1

The correct option is D

incoherent

Explanation for the correct answer:

In the case of option D.

1. The light from a laser beam is said to be highly coherent, which directly means the wavelengths of the beam of laser light are in phase in space and time.
2. This property of being coherent makes lasers very different and unique from normal light sources; and very hazardous to the eyes or skin.
3. Thus option D is the correct option.

Explanation for the incorrect answers:

In the case of option A.

1. Lasers basically work by getting a bunch of atoms, which are all excited.
2. An excited atom is said to have enough energy to jolt it from its normal resting 'ground' state into a higher-energy 'excited' state.
3. Due to these bunch of excited atoms, laser is highly intense.
4. Thus option A is the incorrect option.

In the case of option B.

1. Laser light beam has a very small divergence. that's why It is highly directional.
2. Directionality of the emitted laser beam is governed by the mirror configuration of the laser cavity.
3. Thus, option B is the incorrect option.

In the case of option C.

1. The light from a laser typically comes from one atomic transition with a single precise wavelength.
2. So the laser light has a single spectral color and is almost the purest monochromatic light available.
3. Thus, option C is the incorrect option.

Thus option D is the correct option.