The video tutorial by Paul from Physics High explains the principles and workings of lasers. It covers the applications of lasers in various fields, the properties that define a laser, and the atomic structure involved in laser operation. The tutorial delves into the concepts of stimulated emission, photon amplification, and population inversion, which are crucial for laser functionality. It also describes the construction of a laser using mirrors to create a standing wave, resulting in a coherent and collimated beam. The video aims to provide a comprehensive understanding of how lasers work.

What are the three main properties that define a laser?

• Monochromatic, coherent, collimated

• Multicolored, coherent, collimated

• Multicolored, incoherent, diffused

• Monochromatic, incoherent, diffused

Which of the following is NOT a common use of lasers?

• Eye surgery

• Supermarket scanning

• Cooking food

• Industrial applications

According to the Bohr model, electrons exist in:

• Random orbits

• Chaotic orbits

• Discrete orbits

• Continuous orbits

What happens when a photon with energy exactly equal to the difference between two energy levels is absorbed by an electron?

• The electron emits a photon

• The electron remains in the same energy level

• The electron disappears

• The electron jumps to a higher energy level

What is the principle behind the energy of a photon being released when an electron drops to a lower energy level?

• E = mc^2

• E = kT

• E = mv^2

• E = hf

What is the main difference between spontaneous and stimulated emission?

• Stimulated emission occurs without external influence

• Stimulated emission does not require an external photon

• Spontaneous emission requires an external photon

• Spontaneous emission occurs without external influence

What is population inversion in the context of lasers?

• More electrons in the ground state than in the excited state

• Equal number of electrons in the ground and excited states

• More electrons in the excited state than in the ground state

• No electrons in the excited state

How is population inversion achieved in a three-level laser system?

• By using a metastable state

• By using random energy levels

• By using a single energy level

• By using continuous energy levels

What role do mirrors play in the functioning of a laser?

• They absorb photons

• They amplify the light by reflecting photons back and forth

• They change the color of the light

• They diffuse the light

Why is a laser beam collimated?

• Because of the incoherent nature of the light

• Because of the standing wave set up between mirrors

• Because of the use of lenses

• Because of the random direction of photons