Lasers: a Collection of Atoms Has 20% of the Sample

question 35

Multiple Choice

Lasers: A collection of atoms has 20% of the sample in a state above the ground state. If these emit coherent radiation, what is the wavelength of the laser light produced? (c = 3.00 × 10⁸ m/s, h = 6.626 × 10^-34 J ∙ s, 1 eV = 1.60 × 10^-19 J)

• A) 210 nm
• B) 91 nm
• C) 340 nm
• D) 34 nm

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Definitions:

Phase Current

The current flowing through one phase circuit in a polyphase system, which could vary in magnitude and phase angle compared to currents in other phases.

Wye

A connection in three-phase systems where the ends of each phase are connected at a common point, forming a Y-like shape.

Delta

A method of connection for a three-phase electrical circuit that forms a triangle-like configuration.

Balanced Three-Phase System

A three-phase electrical system where all three phases carry equal currents and have the same voltage magnitude but are out of phase with each other by 120 degrees.