Question

Which of the following is not a characteristic of a laser light?

• A. Highly coherent
• B. Highly penetrating
• C. Highly intense
• D. Highly divergent

Hint:

Remember the four main properties of laser light: 1. {Monochromaticity:} Very narrow range of wavelengths (single color). 2. {Coherence:} All waves are in phase. 3. {Directionality:} Travels in a straight, narrow beam (low divergence). 4. {High Intensity:} Concentrated power. "Highly divergent" is the opposite of Directionality.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
A laser (Light Amplification by Stimulated Emission of Radiation) produces a unique form of light with several distinct properties that differentiate it from ordinary light sources like a light bulb. We need to identify which option is not one of these properties.
Step 2: Detailed Explanation:
Let's analyze the fundamental characteristics of laser light:

Coherence: Laser light is highly coherent. This means all the photons in the beam are in phase with each other, both spatially and temporally. This is a defining characteristic. So, (A) is a characteristic.
Intensity: Because the energy is concentrated in a very narrow beam, lasers can achieve extremely high intensity (power per unit area). So, (C) is a characteristic.
Directionality (Low Divergence): Laser light is highly directional, meaning it travels as a narrow, parallel beam with very little spread or divergence over long distances. The statement "Highly divergent" is the direct opposite of this key property.
Penetrating Power: This term is usually associated with high-energy radiation like X-rays or gamma rays. While a very high-power laser can cut through materials, "highly penetrating" is not considered a fundamental characteristic of laser light in the same way as coherence or directionality. The interaction is typically thermal or ablative at the surface, not deep penetration through matter.
Step 3: Final Answer:
Comparing the options, "Highly divergent" is a direct contradiction of a primary characteristic of laser light (which is low divergence). While "highly penetrating" is also not a characteristic, "highly divergent" represents the antithesis of the well-known property of directionality or collimation. In the context of physics questions, the direct opposite of a key feature is often the intended incorrect option. Therefore, "Highly divergent" is the best answer for what is not a characteristic of laser light.