Q1: LASER

ANS:A - stands for Light Amplification by Stimulated Emission of Radiation.

"LASER" stands for "Light Amplification by Stimulated Emission of Radiation." This term encapsulates the fundamental principles behind how lasers function. Let's break down the phrase:

1. Light Amplification: This refers to the process by which the energy of photons (particles of light) is increased within the laser medium. In a laser, atoms or molecules within the medium are excited to higher energy states, typically through the input of energy from an external source such as electrical current or light. These excited atoms or molecules then emit photons. This process is known as amplification because the number of photons is increased within the laser medium.
2. Stimulated Emission: Stimulated emission occurs when an incoming photon interacts with an excited atom or molecule within the laser medium. This interaction causes the excited atom or molecule to release a second photon that is identical in wavelength, phase, and direction to the incoming photon. The released photon has the same energy and direction as the stimulating photon. This process leads to the emission of coherent (in-phase) light.
3. of Radiation: The term "radiation" in this context refers to electromagnetic radiation, which includes light. Therefore, "radiation" here simply emphasizes that the emitted photons are in the form of electromagnetic waves.

Combining these elements, "Light Amplification by Stimulated Emission of Radiation" describes the process by which a laser produces coherent and intense beams of light. It highlights the key mechanisms involved: the amplification of photons within the laser medium and the emission of coherent light through stimulated emission processes. This acronym succinctly captures the essential principles that underlie laser technology.