LASER acronym stands for Light Amplification by Stimulated Emission of Radiation.

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

Answer: (A)

LASER stands for Light Amplification by Stimulated Emission of Radiation. This expansion is correct because the beam produced by a laser is light that is amplified in intensity. The key mechanism is stimulated emission: a photon passing through the gain medium prompts excited atoms to emit more photons that have the same wavelength, phase, and direction, creating a coherent, amplified beam of light. Radiation simply refers to the electromagnetic energy carried by those photons.

The other options fail because they replace Light with other words or swap in spontaneous emission, which does not provide the controlled, coherent amplification lasers rely on. They might also alter the phrase to “Laser…” or use Activation, which aren’t the established terms for the acronym.