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Questions and Answers
Which branch of physics studies the behavior and properties of light, including its interactions with matter?
Which branch of physics studies the behavior and properties of light, including its interactions with matter?
- Optics (correct)
- Thermodynamics
- Quantum Mechanics
- Acoustics
Besides visible light, which other types of electromagnetic radiation are sometimes included in the study of optics?
Besides visible light, which other types of electromagnetic radiation are sometimes included in the study of optics?
- Cosmic rays and Terahertz waves
- X-rays and Microwaves
- Radio waves and Gamma rays
- Ultraviolet (UV) and Infrared (IR) (correct)
What fundamental principle is assumed in geometric optics regarding the travel of light?
What fundamental principle is assumed in geometric optics regarding the travel of light?
- Light only travels in wave-like patterns.
- Light travels in straight lines within a uniform medium. (correct)
- Light travels in curves due to gravitational fields.
- Light instantly occupies all points in space.
Which of the following phenomena is best described by geometric optics?
Which of the following phenomena is best described by geometric optics?
What happens to the direction of light when it encounters an interface between two different media, according to geometric optics?
What happens to the direction of light when it encounters an interface between two different media, according to geometric optics?
In the context of optics, what term describes the phenomenon where light 'bounces' off a surface?
In the context of optics, what term describes the phenomenon where light 'bounces' off a surface?
According to the law of reflection, what is the relationship between the angle of incidence and the angle of reflection?
According to the law of reflection, what is the relationship between the angle of incidence and the angle of reflection?
If a light ray strikes a mirror at an angle of 30 degrees relative to the normal, what is the angle of the reflected ray relative to the normal?
If a light ray strikes a mirror at an angle of 30 degrees relative to the normal, what is the angle of the reflected ray relative to the normal?
What term describes the phenomenon where light returns in a direction parallel to its original direction after being reflected by two or more surfaces?
What term describes the phenomenon where light returns in a direction parallel to its original direction after being reflected by two or more surfaces?
In retroreflection with two mirrors, what angle is typically formed between the two mirrors to cause light to return parallel to its incident direction?
In retroreflection with two mirrors, what angle is typically formed between the two mirrors to cause light to return parallel to its incident direction?
Which of the following is an example of retroreflection in everyday applications?
Which of the following is an example of retroreflection in everyday applications?
What is the optical phenomenon where light changes direction as it passes from one medium to another?
What is the optical phenomenon where light changes direction as it passes from one medium to another?
Does light always travel at the same speed, regardless of the medium through which it passes?
Does light always travel at the same speed, regardless of the medium through which it passes?
Which term describes the measure of how much the speed of light is reduced inside a medium compared to its speed in a vacuum?
Which term describes the measure of how much the speed of light is reduced inside a medium compared to its speed in a vacuum?
What is the mathematical relationship for calculating the refractive index (n) of a medium, where c is the speed of light in a vacuum and v is the speed of light in the medium?
What is the mathematical relationship for calculating the refractive index (n) of a medium, where c is the speed of light in a vacuum and v is the speed of light in the medium?
How does the speed of light in a material relate to its refractive index?
How does the speed of light in a material relate to its refractive index?
What is the optical path length (OPL)?
What is the optical path length (OPL)?
If light travels through a vacuum and then through a piece of glass with the same geometric length, how will the optical path length (OPL) compare in each medium?
If light travels through a vacuum and then through a piece of glass with the same geometric length, how will the optical path length (OPL) compare in each medium?
Which equation correctly describes Snell's Law, relating the angles of incidence ($\theta_1$) and refraction ($\theta_2$) to the refractive indices ($n_1$ and $n_2$) of two media?
Which equation correctly describes Snell's Law, relating the angles of incidence ($\theta_1$) and refraction ($\theta_2$) to the refractive indices ($n_1$ and $n_2$) of two media?
According to Snell's Law, when light passes from a medium with a lower refractive index to a medium with a higher refractive index, what happens to the light beam?
According to Snell's Law, when light passes from a medium with a lower refractive index to a medium with a higher refractive index, what happens to the light beam?
Light is incident from air ($n_1 = 1.0$) onto a glass surface ($n_2 = 1.5$) at an angle of 30 degrees. What is the angle of refraction in the glass?
Light is incident from air ($n_1 = 1.0$) onto a glass surface ($n_2 = 1.5$) at an angle of 30 degrees. What is the angle of refraction in the glass?
When does total internal reflection (TIR) occur?
When does total internal reflection (TIR) occur?
What is the critical angle in the context of total internal reflection?
What is the critical angle in the context of total internal reflection?
For total internal reflection to occur, which condition must be met regarding the incident angle ($\theta_1$) and the critical angle ($\theta_c$)?
For total internal reflection to occur, which condition must be met regarding the incident angle ($\theta_1$) and the critical angle ($\theta_c$)?
Light travels from glass ($n_1 = 1.5$) into air ($n_2 = 1.0$). What is the critical angle at the glass-air interface?
Light travels from glass ($n_1 = 1.5$) into air ($n_2 = 1.0$). What is the critical angle at the glass-air interface?
Where is Total Internal Reflection (TIR) primarily utilized?
Where is Total Internal Reflection (TIR) primarily utilized?
What is the purpose of cladding in an optical fiber?
What is the purpose of cladding in an optical fiber?
In the context of optical fibers, what is the 'acceptance angle'?
In the context of optical fibers, what is the 'acceptance angle'?
If diamonds have a high refractive index, which leads to a smaller critical angle, what visual effect does this cause?
If diamonds have a high refractive index, which leads to a smaller critical angle, what visual effect does this cause?
What is responsible for the effect known as 'chromatic dispersion'?
What is responsible for the effect known as 'chromatic dispersion'?
Of the colors in visible light, which typically refracts the most when passing through a prism?
Of the colors in visible light, which typically refracts the most when passing through a prism?
Which of the following phenomena is a direct consequence of chromatic dispersion?
Which of the following phenomena is a direct consequence of chromatic dispersion?
Why does white light split into different colors when passing through a prism?
Why does white light split into different colors when passing through a prism?
How does the refractive index of a medium generally vary with the wavelength of light?
How does the refractive index of a medium generally vary with the wavelength of light?
In a scenario where a light ray crosses multiple interfaces of different media, which of the listed options is MOST accurate, assuming $n_1$, $n_2$ and $n_3$ are the refractive indexes of medium 1, 2, and 3, respectively?
In a scenario where a light ray crosses multiple interfaces of different media, which of the listed options is MOST accurate, assuming $n_1$, $n_2$ and $n_3$ are the refractive indexes of medium 1, 2, and 3, respectively?
Consider the following scenario: Light is traveling from a medium with an index of refraction $n_1$ to another medium with an index of refraction $n_2$. If the incident angle is exactly at the critical angle, what will the angle of refraction be?
Consider the following scenario: Light is traveling from a medium with an index of refraction $n_1$ to another medium with an index of refraction $n_2$. If the incident angle is exactly at the critical angle, what will the angle of refraction be?
Monochromatic light is incident on a prism with an apex angle of $A$ and refractive index $n$. If the angle of incidence is adjusted to the minimum deviation condition, and the angle of deviation is $\delta_m$, what is the relationship between $A$, $n$, and $\delta_m$?
Monochromatic light is incident on a prism with an apex angle of $A$ and refractive index $n$. If the angle of incidence is adjusted to the minimum deviation condition, and the angle of deviation is $\delta_m$, what is the relationship between $A$, $n$, and $\delta_m$?
Flashcards
What is Optics?
What is Optics?
Branch of physics studying light behavior, properties, and interactions with matter, including instrument construction.
Speed of Light
Speed of Light
Light travels at approximately 3.0 x 10^8 m/s in a vacuum.
Light's Linear Path
Light's Linear Path
Light travels in straight lines, creating shadows when blocked by objects.
Light-Matter Interactions
Light-Matter Interactions
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Light as Waves
Light as Waves
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Geometric Optics
Geometric Optics
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Plane of Incidence
Plane of Incidence
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Law of Reflection
Law of Reflection
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Retroreflector
Retroreflector
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Retroreflection
Retroreflection
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Refraction
Refraction
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Index of Refraction
Index of Refraction
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Optical Path Length (OPL)
Optical Path Length (OPL)
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Snell's Law
Snell's Law
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Refraction into Denser Medium
Refraction into Denser Medium
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Refraction into Less Dense Medium
Refraction into Less Dense Medium
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Index of Refraction and Wavelength
Index of Refraction and Wavelength
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Chromatic Dispersion of White light
Chromatic Dispersion of White light
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Greatest Refraction
Greatest Refraction
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Least Refraction
Least Refraction
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Total Internal Reflection
Total Internal Reflection
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Critical Angle of Incidence
Critical Angle of Incidence
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Acceptance Angle
Acceptance Angle
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Study Notes
Introduction to Optics
- Optics is the physics branch studying light behavior and properties
- It includes interactions with matter and instrument construction
- Optics involves the study of visible light
- Also known as Photonics, it extends to UV and IR
Branches of Optics
- Geometric Optics deals with light rays
- Wave Optics studies light waves
- Quantum Optics deals with quantum aspects of light
Basic Properties of Light
- Light travels fast at c = 3.0 x 10^8 m/s, or 300,000,000 m/s
- This is 300 Earth diameters per second
- Light travels in straight lines, resulting in shadows
- Light has properties of Reflection, Absorption and Transmission
- While light travels in straight lines, individual photons (bundles of energy) travel as waves
- Electromagnetic Wave: E(z,t) = Epcos(ωt – kz), where:
- Speed of light = c = 3 x 10^8 m/s in a vacuum
- Frequency = v, Angular frequency = ω = 2πν, Wavelength = λ = c/v, Wave vector = k = 2π/λ
- The Wave vector characterizes the phase and has a Vector in the direction of propagation
Geometric Optics
- Most fundamental laws of optics were discovered before electromagnetism
- Laws classified under Geometric Optics describe most observed phenomena in daily life
- Light travels in a fixed direction as a straight line in a uniform medium
- Light changes direction when meeting an interface of different media
Plane of Incidence
- The normal, incident, reflected, and refracted rays lie in a plane perpendicular to the reflecting surface
Law of Reflection
- The angle of reflection equals the angle of incidence
- Incident ray hits the first mirror
- The reflected ray is directed toward the second mirror
- There is a second reflection from the second mirror
- Apply the law of reflection and geometry to determine information about rays
Retroreflection
- When mirrors are at 90°, the reflected beam returns parallel to the incident beam
Applications of Retroreflectors
- Eyeshine occurs from retroreflectors
- Type of transparent sphere is visible in the cat's eyes
- Stop signs appear to glow due to many retroreflecting spheres
- Retroreflectors have been placed on the Moon
Light Propagation through Different Media
- When light travels through a transparent medium and meets a boundary, it's partly reflected and partly refracted
- Refraction is a change in the speed and direction of a wave passing from one medium into another
Index of Refraction (Refractive Index)
- The speed of light in any material is less than in a vacuum
- Index of refraction (n) is defined as: n = (speed of light in vacuum) / (speed of light in medium)
- n = c/v > 1, where v=c/n
- The higher the refractive index, the slower the light in the medium
Optical Path Length (OPL)
- Describes light's travel length in a medium
- OPL = geometric length of the light path × refractive index
- Given the same geometric length, OPL is shorter in vacuum than glass
Refraction (Snell's Law)
- Snell's Law: n₁ sin θ₁ = n₂ sin θ₂
- When light enters a denser medium (n₁ < n₂), θ₁ > θ₂, and the light beam is bent towards the normal
- When light enters a less dense medium (n₁ < n₂), θ₁ < θ₂, and the light beam is bent away from the normal
Key steps for solving refraction problems
- Find the interface
- Draw the vertical plane
- Search for n1, n2, θ1, θ2
- Solve n1 Sin θ1= n2 Sin θ2
Chromatic Dispersion
- White light consists of many colours
- Different colours have different refractive indices
- An index of refraction is greater for shorter wavelengths
- Dispersion is a dependence of n on λ
- Snell's law indicates that light of different wavelengths is bent at different angles if incident on a refracting material
- When a beam with blue and red light is refracted through a surface, the blue component bends more than the red component from the incident ray
- A rainbow is the most charming example of chromatic dispersion
- Violet light refracts the most
- Red light refracts the least
Total Internal Reflection
- When light goes from a higher to a lower refractive index, the refracted rays are bent away from the normal
- At a particular angle of incidence, called the critical angle, the refracted ray moves parallel to the boundary, so θ₂ = 90°
- If the incident angle > critical angle, the beam is reflected at the boundary
- From Snell's Law: sinθc = n2/n1 (for n₁ > n₂)
- If θ₁ ≥ θc , total internal reflection occurs
Diamonds and TIR
- θc for diamond in air is 24° (n = 2.4)
- As a result, any ray approaching surface at an angle greater than θc will be reflected back into the stone
- Proper cutting makes diamonds brighter
Applications of Total Internal Reflection
- Core and Cladding of the optical fibre have different refractive indices
- Touch screen panels arise as a result of frustrated TIR
- Telecomm Fibre has a core a cladding
- The core is 10 μm
- The cladding is 125 μm
Acceptance Angle of Optical Fibre
- θᵢ defines an acceptance angle at which lights can be coupled to the optional fibre
- No lights can be coupled beyond the acceptance angle
- n (air) Sin θᵢ =n(fiber) Sin θᵣ
- n (fiber) Sin θC =n(air) Sin 90° = 1
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