The essential condition required for Laser action to occur in a medium is known as: MCQ with Answer and Explanation

The essential condition required for Laser action to occur in a medium is known as:

A. Spontaneous emission

B. Photoelectric emission

C. Thermal equilibrium

D. Population inversion

Answer: Option D

Solution (By JKExamLibrary)

Laser (Light Amplification by Stimulated Emission of Radiation) requires that more atoms exist in a high-energy excited state than in a lower energy state. This unnatural, non-equilibrium condition is called 'population inversion'. Without it, absorption would dominate over stimulated emission, and the beam would not be amplified.

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Question #1 Report Error

If the intensity of a sound is mathematically increased by a factor of 100, its loudness level in decibels (dB) increases strictly by:

A. 10 dB

B. 2 dB

C. 20 dB

D. 100 dB

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Correct Answer: Option C

Explanation:
The loudness level in decibels is calculated as L = 10 * log10(I / I0). If intensity I becomes 100I, the new level L' = 10 * log10(100I / I0) = 10 * [log10(100) + log10(I / I0)] = 10 * [2 + L/10] = 20 + L. Therefore, the loudness explicitly increases by 20 dB.

This question belongs to: Science Physics