Q4 - GenPhy2 Flashcards by Yuan Navera

Have you ever noticed the rainbow colors on a soap bubble or the shimmering patterns
on an oil slick? – This happens due to the

interference of light.

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Is when multiple light waves overlap & either increase or decrease in
amplitude. This can be constructive or destructive, depending on how the
waves align.

Interference of Light

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When two light waves form a superimposed wave or higher amplitude.

Constructive Interference

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When two light waves form a superimposed
wave or lower amplitude.

Destructive Interference

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Conditions for Interference:

Light must be coherent (same frequency & constant phase difference).
Light must have the same wavelength.

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The result is s stronger & more intense light wave because their amplitudes
(wave heights) add up.

Constructive Light Interference

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Eyeglasses use ____ ____ to reduce glare & unwanted
reflections through anti-reflective (AR) coatings. This helps improve vision
clarity & reduces eye strain.

Destructive Light Interference

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Thin-film interference is a natural phenomenon that occurs when light waves
reflection off the top & bottom of a thin film. This interference creates colorful
patterns, such as those seen in soap bubbles & oil films.

Interference in Thin Films

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Famous experiment by Thomas Young.

Double-slit Experiment

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Light passes through two narrow slits, creating an interference pattern of bright
& dark fringes on a screen.

Double-slit Experiment

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Demonstrates the wave nature of light.

Double-slit Experiment

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Is a phenomenon that occurs when light passes through a narrow slit, causing
it to bend & spread out into a pattern of bright & dark bands.

Single-slit Diffraction

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Based on the work of Albert Einstein, this theory helps explain how objects
behave when they move close to the speed of light.

Special Theory of Relativity

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6 Special Theories of Relativity

Postulates of the Special Theory of Relativity
Coordinate Transformations
Time Dilation
Length Contraction
Relativistic Momentum & Energy
Relativistic Doppler Effect

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Postulates of the Special Theory of Relativity:

Postulate 1: The Principle of Relativity
Postulate 2: The Constancy of the Speed of Light

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The laws of physics are the same in all inertial frames of reference (in non-accelerating systems).

Postulate 1: The Principle of Relativity

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This means if you are in a moving spaceship or standing on Earth, physics works the same way.

Postulate 1: The Principle of Relativity

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The speed of light in vacuum is always the same for all observers, regardless of their motion or the motion of the light source.

Postulate 2: The Constancy of the Speed of Light

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Speed of Light

3x10^8

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In regular motion (slow speeds), we use the Galilean Transformation to change coordinates from one reference frame to another.

Coordinate Transformation

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However, at very high speeds (close to light speed), this no longer works properly – this is where the Lorentz Transformation comes in.

Coordinate Transformations

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It’s a set of equations that relate the position & time coordinates between two
observers moving relative to each other at constant speed.

Lorentz Transformation

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It corrects for the fact that time & space can stretch or compress when you move near the speed of light.

Lorentz Transformation

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According to relativity, time slows down for objects moving close to the speed
of light.

Time Dilation

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Objects moving at relativistic speeds (near the speed of light) appear shorter in the direction of motion when observed from a stationary frame.

Length Contraction

When an object moves close to light speed, its momentum increases more than expected.

Relativistic Momentum & Energy - Momentum at High Speeds

Einstein discovered that mass & energy are related. E = mc^2

Relativisitc Momentum & Energy - Total Energy

The Doppler Effect describes how the frequency of light (or any wave) changes if the source is moving toward or away from you.

Relativistic Doppler Effect

LASER

Light Amplification by Stimulated Emission of Radiation

SCUBA

Self-Contained Underwater Breathing Apparatus

Dutch scientist Christiaan Huygens proposed the wave theory of light, which argued that light behaves like a wave.

Wave Theory of Light | Early Foundations: Optics & the Nature of Light

**James Clerk Maxwell** unified electricity & magnetism into the theory of electromagnetism with his set of equations, known as Maxwell’s equations.

Electromagnetic Theory of Light | Early Foundations: Optics & the Nature of Light

Maxwell derived that light is an electromagnetic wave – a wave consisting of **oscillating electric & magnetic fields** that propagate through space.

Electromagnetic Theory of Light | Early Foundations: Optics & the Nature of Light

According to Maxwell, light does not require a medium like air or glass to propagate. Instead, it travels through what was once thought to be “ether,” but later, this **“ether” concept was abandoned after the Michelson-Morley** experiment in **1887,** leading to the development of **Einstein’s theory of special relativity.**

Maxwell's Equations of Light | The Role of Electromagnetism

One of Maxwell’s crucial results was that the speed of light (denoted as c) could be derived from the **electric & magnetic properties of the vacuum.** The

The Speed of Light & Electromagnetic Waves | The Role of Electromagnetism in Optics

This connection between light & electromagnetism was later confirmed by the work of **Heinrich Hertz,** who generated & detected electromagnetic waves in the laboratory in the late 1880s.

The Speed of Light & Electromagnetic Waves | The Role of Electromagnetism in Optics

Following Maxwell’s equations, the idea that light is just one form of electromagnetic radiation became solidified. The entire electromagnetic spectrum – from radio waves to microwaves, infrared, visible light, ultraviolet, X-rays, & gamma rays – was understood as varying frequencies of the same underlying phenomenon, electromagnetic waves.

Light as an Electromagnetic Wave | The Unification of Electromagnetic Theory & Optics

Optical Phenomena in Terms of Electromagnetism: | The Unification of Electromagnetic Theory & Optics

* Reflection & Refraction * Interference & Diffraction * Polarization

These classical optical phenomena could now be explained in terms of electromagnetic wave behavior.

Reflection & Refraction

The wave-like properties of light that result in interference & diffraction patterns were fully understood in the context of Maxwell’s theory.

Interference & Diffraction

Which is the alignment of the oscillations of light waves, could also be explained using the electric field component of the electromagnetic wave.

Polarization

In the early 20th century, experiments such as the photoelectric effect (discovered by Heinrich Hertz & later explained by Albert Einstein in 1905) demonstrated that light exhibits both wave-like & particle-like properties. This was the birth of quantum theory

The Birth of Quantum Mechanics | Quantum Theory & its Impact on Electromagnetism & Optics

Light could be described as both electromagnetic waves & **discrete packets of energy** called photons.

THe Birth of Quantum Mechanics | Quantum Theory & Its Impact on Electromagnetism & Optics

The interaction of electromagnetic radiation with matter (such as atoms & electrons) could be described by quantum electrodynamics (QED), developed by **Richard Feynman, Julian Schwinger, & Sin-Itiro Tomonaga.**

Eletromagnetic Waves in the Quantum Era | Quantum Theory & its Impact on Electromagnetism & Optics

The interaction of electromagnetic radiation with matter (such as atoms & electrons) could be described by quantum electrodynamics (QED), developed by ____ ____ ____

Richard Feynman, Julian Schwinger, & Sin-Itiro Tomonaga.

Early work in optics led to the wave theory of light, which laid the groundwork for later developments in electromagnetism.

Wave Theory

Maxwell’s unification of electricity & magnetism established that light is an electromagnetic wave.

Maxwell's Equations

Maxwell derived the speed of light from electromagnetic constants, solidifying the connection between optics & electromagnetism.

The Speed of Light

Later developments in ____ ____ further refined our understanding of light, showing its wave particle duality & extending the scope of electromagnetic theory.

Quantum Mechanics

Today, optics continues to be shaped by electromagnetism, with cutting-edge technologies emerging from the combination of both fields, such as in quantum optics & photonics.

Modern Applications

Occurs when light strikes a surface & bounces back into the same medium.

Reflection

The angle of incidence is always equal to the angle of reflection.

Reflection

Are a common example of surfaces that reflect light, allowing us to see our image.

Mirrors

The law of reflection applies to all types of reflective surfaces, such as water or polished metal.

Reflection

is responsible for phenomena like echo & the formation of images in optical devices.

Reflection

Refraction happens when light passes from one medium to another, changing its speed & direction.

Refraction

When light moves from air into water, it bends towards the normal due to the change in speed.

Refraction

The amount of bending is determined by the refractive indices of the two mediums involved.

Refraction

use refraction to focus light, forming images in devices like glasses & cameras.

Lenses

explains why a pencil looks bent when placed in a glass of water.

Refraction

occurs when light hits a surface & bounces back into the same medium.

Reflection of Light

happens when light passes from one medium to another, causing the light to bed due to a change in its speed. This bending occurs because light travels at different speeds in different materials.

Refraction of Light