What does Laser stand for?

• A. Light Amplification by Stimulated Emission of Radiation
• B. Light Amplification by Stimulated Emission of Radiation
• C. Light Amplification by Spontaneous Emission of Radiation
• D. Light Emission by Stimulated Emission of Radiation

Answer: (A)

Light Amplification by Stimulated Emission of Radiation explains laser. Each part highlights how a laser works: Light refers to photons; Amplification means the light intensity is increased inside a gain medium; Stimulated Emission is when an incoming photon prompts an excited atom to emit another photon that matches in phase, frequency, and direction, leading to a strong, coherent beam; Radiation is the electromagnetic energy released.

Choosing the version that uses Spontaneous Emission would produce light that is random in phase and direction, not the coherent beam lasers are known for. The option that says Light Emission by Stimulated Emission swaps Amplification for Emission, which misses the essential idea that the process builds up light intensity rather than merely emitting light.