Q4 - GenPhy2 Flashcards
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.
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
When two light waves form a superimposed wave or higher amplitude.
Constructive Interference
When two light waves form a superimposed
wave or lower amplitude.
Destructive Interference
Conditions for Interference:
- Light must be coherent (same frequency & constant phase difference).
- Light must have the same wavelength.
The result is s stronger & more intense light wave because their amplitudes
(wave heights) add up.
Constructive Light Interference
Eyeglasses use ____ ____ to reduce glare & unwanted
reflections through anti-reflective (AR) coatings. This helps improve vision
clarity & reduces eye strain.
Destructive Light Interference
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
Famous experiment by Thomas Young.
Double-slit Experiment
Light passes through two narrow slits, creating an interference pattern of bright
& dark fringes on a screen.
Double-slit Experiment
Demonstrates the wave nature of light.
Double-slit Experiment
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
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
6 Special Theories of Relativity
- Postulates of the Special Theory of Relativity
- Coordinate Transformations
- Time Dilation
- Length Contraction
- Relativistic Momentum & Energy
- Relativistic Doppler Effect
Postulates of the Special Theory of Relativity:
Postulate 1: The Principle of Relativity
Postulate 2: The Constancy of the Speed of Light
The laws of physics are the same in all inertial frames of reference (in non-accelerating systems).
Postulate 1: The Principle of Relativity
This means if you are in a moving spaceship or standing on Earth, physics works the same way.
Postulate 1: The Principle of Relativity
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
Speed of Light
3x10^8
In regular motion (slow speeds), we use the Galilean Transformation to change coordinates from one reference frame to another.
Coordinate Transformation
However, at very high speeds (close to light speed), this no longer works properly – this is where the Lorentz Transformation comes in.
Coordinate Transformations
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
It corrects for the fact that time & space can stretch or compress when you move near the speed of light.
Lorentz Transformation
According to relativity, time slows down for objects moving close to the speed
of light.
Time Dilation
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
