Wave Optics Quiz
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Questions and Answers

What is the main reason visible-light microscopes cannot image individual atoms?

  • Atoms do not emit any light detectable by visible-light microscopes.
  • Visible light does not exhibit interference patterns.
  • Visible light cannot penetrate matter effectively.
  • Visible light has a longer wavelength than the size of an atom. (correct)

In the phenomenon of constructive interference, what occurs when two coherent waves meet?

  • The displacement is reduced to zero.
  • The waves cancel each other out completely.
  • The total displacement is the difference of individual displacements.
  • The total displacement is the sum of individual displacements. (correct)

Why do computer chip manufacturers prefer x-rays for etching chips over visible light?

  • X-rays have a higher energy and shorter wavelength. (correct)
  • Visible light can cause damage to silicon chips.
  • X-rays are easier to control than visible light.
  • X-rays can penetrate materials more effectively than visible light.

What does the principle of superposition state about multiple waves at a point?

<p>The total displacement is the vector sum of the displacements of the individual waves. (C)</p> Signup and view all the answers

Which phenomenon is primarily studied in wave optics that is not valid in geometric optics?

<p>Interference of waves (D)</p> Signup and view all the answers

What is the relationship between the radius of dark rings and the natural numbers?

<p>Radius of dark rings is proportional to the square root of even natural numbers. (C)</p> Signup and view all the answers

For bright bands, what is the formula that relates the radius to the band number?

<p>rm² = 2Rt (C)</p> Signup and view all the answers

What is the expression for the diameter of the nth dark ring?

<p>Dn = 2 √n (C)</p> Signup and view all the answers

How can the wavelength of monochromatic light be determined?

<p>By measuring the diameter of bright and dark rings. (B)</p> Signup and view all the answers

What formula is used to express the radius of curvature in relation to the radius of dark rings?

<p>rn² = 2Rt (D)</p> Signup and view all the answers

When considering the radius of bright rings, how is this radius expressed in terms of the band number?

<p>rm = √(2m + 1) (C)</p> Signup and view all the answers

What happens to the air film when the gap between the lens and glass plate is filled with liquid?

<p>The air film is replaced by a liquid film. (C)</p> Signup and view all the answers

In the context of dark rings, what is the behavior of the radius as the band number increases?

<p>It increases proportionally to the square root of the band number. (C)</p> Signup and view all the answers

What is the geometric path difference between ray 1 and ray 2?

<p>BF + FD - BH (D)</p> Signup and view all the answers

What effect does reflection at the boundary of a rarer to denser medium have on the path?

<p>Path change of λ/2 (B)</p> Signup and view all the answers

What condition must be met for constructive interference (maxima) to occur?

<p>Δ = (2m + 1)λ (B)</p> Signup and view all the answers

Which equation gives the optical path difference Δ when considering the reflections and thin film?

<p>Δ = μ(BF + FD) - BH (C)</p> Signup and view all the answers

In the expression for BH, which of the following variables denotes the angle of incidence?

<p>i (A)</p> Signup and view all the answers

Which of the following statements about the path changes in waves is correct?

<p>Only paths from denser to rarer mediums change (A)</p> Signup and view all the answers

What does 'μ' represent in the equations provided?

<p>Index of refraction (C)</p> Signup and view all the answers

What expression represents the relationship between BH and the angles of incidence and refraction according to Snell’s Law?

<p>BH = 2t*tan(r)*sin(i) (C)</p> Signup and view all the answers

What condition must be met for a minimum in interference to occur?

<p>Δ = (2m + 1)λ (A)</p> Signup and view all the answers

For constructive interference to take place, which of the following equations describes the condition for maxima?

<p>Δ = mλ (B)</p> Signup and view all the answers

What describes a wedge shaped thin film in terms of thickness?

<p>It has zero thickness at one end and increases progressively. (B)</p> Signup and view all the answers

What happens to the rays BC and DE in a wedge shaped film?

<p>They interfere to produce alternating bright and dark fringes. (D)</p> Signup and view all the answers

What accounts for the half wave gain in reflected waves in the interference pattern?

<p>The abrupt jump of π radian in phase reflection from the boundary (C)</p> Signup and view all the answers

If Δ = -λ/2 is used, what is it accounting for in the interference of the wedge film?

<p>The path difference between the interfering rays (D)</p> Signup and view all the answers

Which statement about the fringe pattern in wedge shaped thin films is correct?

<p>White light results in colored fringes due to varying thickness. (A)</p> Signup and view all the answers

In the context of thin film interference, refractive index plays what role?

<p>It influences the speed of light in the film. (D)</p> Signup and view all the answers

What is the condition for the formation of a dark ring in terms of wavelength?

<p>$2 \mu t = n \lambda$ (C), $2 \mu t \cos r = n \lambda$ (D)</p> Signup and view all the answers

How does the diameter of the dark rings change as the order of the ring increases?

<p>The diameter increases but does not increase in the same proportion (A)</p> Signup and view all the answers

At what thickness does the air film start in a Newton's ring experiment?

<p>Zero thickness at the center (C)</p> Signup and view all the answers

Which of the following statements about the central fringe in reflected light is true?

<p>The center fringe is dark (D)</p> Signup and view all the answers

What do the circular fringes in a Newton's ring experiment represent?

<p>Points of varying thickness of the air film (D)</p> Signup and view all the answers

What does the equation for the diameter of the n-th dark ring suggest about the nature of the rings?

<p>The diameter increases with the square root of n (B)</p> Signup and view all the answers

What is the relationship between the radius of curvature of the lens and the diameter of the rings?

<p>Smaller radius of curvature leads to larger diameters (D)</p> Signup and view all the answers

How is the optical path difference expressed for interfering rays at the center of a Newton's ring setup?

<p>$\Delta = \lambda/2$ (C)</p> Signup and view all the answers

What does the optical path length (OPL) account for in its measurement?

<p>The distance light travels and the medium's refractive index (B)</p> Signup and view all the answers

In the context of thin film interference, what is the typical thickness range for an optical medium to be considered a thin film?

<p>0.5 μm to 10 μm (C)</p> Signup and view all the answers

What is the significance of the optical path in optical phenomena?

<p>It helps understand wave interactions based on phase differences. (D)</p> Signup and view all the answers

Which of the following statements best describes the difference between geometrical path and optical path?

<p>Geometrical path is the actual distance, while optical path includes refractive index. (B)</p> Signup and view all the answers

What type of optical medium is classified as a thin film?

<p>A medium with thickness approximately equal to 1 wavelength of visible light (B)</p> Signup and view all the answers

In plane parallel thin films, which factor does not influence the behavior of light?

<p>The temperature of the medium (A)</p> Signup and view all the answers

What happens to light when it encounters a thin film at a certain angle?

<p>Part of the light is reflected while part is transmitted (A)</p> Signup and view all the answers

What is the formula for calculating optical path length (OPL)?

<p>OPL = μ × L (A)</p> Signup and view all the answers

Flashcards

Wave Optics (Physical Optics)

The study of light phenomena where the ray approximation of geometric optics fails, focusing on interference, diffraction, and polarization.

Interference

The phenomenon where two or more coherent waves of light overlap, resulting in a pattern of alternating bright and dark bands due to constructive and destructive interference.

Constructive Interference

When crests of two waves meet, resulting in a larger amplitude, producing a brighter spot.

Destructive Interference

When a crest of one wave meets a trough of another wave, resulting in a smaller amplitude, producing a darker spot.

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Superposition Principle

The superposition principle states that when multiple waves meet at a point, the resulting displacement is the vector sum of individual wave displacements.

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Optical Path

The distance light travels multiplied by the refractive index of the medium it's traveling through.

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Geometrical Path

The actual distance light travels, measured directly.

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Thin Film

A transparent material with a thickness of about one wavelength of visible light (0.5-10 micrometers).

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Plane Parallel Thin Film

A thin film with two parallel surfaces, creating uniform thickness.

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Refraction

The change in the direction of light as it passes from one medium to another.

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rn² = nλR

The relation between the radius of a dark ring (rn), wavelength of light (λ), radius of curvature of the lens (R), and the order of the dark ring (n).

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Radius of dark rings in Newton's rings

The radius of the nth dark ring (rn) in Newton's rings is proportional to the square root of the order of the dark ring (n) and the radius of curvature of the lens (R).

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rm² = (2m+1)λR

The relation between the radius of a bright ring (rm), wavelength of light (λ), radius of curvature of the lens (R), and the order of the bright ring (m).

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Radius of bright rings in Newton's rings

The radius of the mth bright ring (rm) in Newton's rings is proportional to the square root of the odd natural number (2m+1) and the radius of curvature of the lens (R).

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Determining wavelength of light using Newton's rings

The change in the diameter of dark rings can be used to determine the wavelength of light.

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Determining refractive index of liquid using Newton's rings

Replacing the air film with a liquid film in Newton's rings experiment allows for the determination of the refractive index of the liquid.

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Geometric Path Difference

The difference in the distance traveled by two light rays, one traveling through air and the other through a thin film.

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Optical Path Difference

The difference in phase between two light waves, taking into account the optical path length traveled by each wave.

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Optical Path Length

The product of the refractive index of a medium and the geometric path length of light traveling through it.

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Equation for Path Difference between Two Rays

The path difference between two interfering rays is [μ (BF+FD) – 1*(BH)] or [μ (2BF) – BH].

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Condition for Minima (Destructive Interference)

When the optical path difference between two interfering waves is an odd multiple of half the wavelength, destructive interference occurs causing a dark fringe or minimum.

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Condition for Maxima (Constructive Interference)

When the optical path difference between two interfering waves is a whole number multiple of the wavelength, constructive interference occurs causing a bright fringe or maximum.

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Phase Change on Reflection

A phase change of λ/2 occurs when light is reflected at the boundary between a less dense medium and a denser medium. This affects the overall path difference.

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Path Difference Equation for Reflected Light

The equation for path difference due to reflected light is Δ = 2tμcos(r) - λ/2, where Δ is the optical path difference, t is the thickness of the thin film, μ is the refractive index of the film, r is the angle of refraction, and λ is the wavelength of light. This helps predict the interference pattern.

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Optical Path Difference (Δ)

The difference in distance traveled by two light rays interfering, taking into account the phase change upon reflection.

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Wedge Shaped Thin Film

A thin film with varying thickness, creating a gradual change in optical path difference from one end to the other.

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Condition for Maxima (Brightness)

The condition for maximum intensity (bright fringe) in a wedge-shaped thin film, where the optical path difference is a multiple of the wavelength.

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Condition for Minima (Darkness)

The condition for minimum intensity (dark fringe) in a wedge-shaped thin film, where the optical path difference is an odd multiple of half the wavelength.

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Band Width/Fringe Width

The distance between two consecutive bright or dark fringes in a wedge-shaped thin film.

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Angular Fringe Width

The angular separation between two adjacent bright or dark fringes in a wedge-shaped thin film.

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Monochromatic Beam of Light

A narrow, straight band of light that is typically used for interference experiments.

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Dark Ring Formation Condition

The condition for the formation of a dark ring in Newton's rings experiment, where μ is the refractive index of the medium, t is the thickness of the air film, r is the angle of refraction, n is the order of the dark ring, and λ is the wavelength of light.

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Radius of nth Dark Ring

The formula for the radius of the nth dark ring in Newton's rings, where rn is the radius of the nth dark ring, R is the radius of curvature of the lens, and λ is the wavelength of light.

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Diameter of nth Dark Ring

The formula for the diameter of the nth dark ring in Newton's rings, where Dn is the diameter of the nth dark ring, R is the radius of curvature of the lens, and λ is the wavelength of light.

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Newton's Rings Shape and Spacing

The observation that Newton's rings are circular, not evenly spaced, and get closer together as you move away from the center.

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Central Fringe in Newton's Rings

The observation that the central fringe in Newton's rings is dark in reflected light, due to the path difference creating destructive interference.

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Determining Liquid Refractive Index

Replacing the air film in Newton's rings with a liquid film allows for the determination of the liquid's refractive index.

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Determining Wavelength

The change in diameter of the dark rings in Newton's rings can be used to determine the wavelength of light.

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Study Notes

Wave Optics

  • Wave optics studies phenomena where the ray approximation of geometric optics isn't suitable, including interference, diffraction, and polarization.
  • Light has an electromagnetic nature, consisting of oscillating electric and magnetic fields perpendicular to each other and the direction of wave motion.
  • Interference occurs when two or more coherent light waves superpose, creating alternating bright and dark bands due to the redistribution of light energy.
  • The superposition principle states that the total displacement at a point is the vector sum of individual wave displacements.
  • Constructive interference happens when a crest of one wave meets a crest of another, resulting in a larger displacement.
  • Destructive interference occurs when a crest meets a trough, leading to a smaller displacement.
  • Thin films exhibit interference due to reflected light. A thin film is typically a transparent material with thickness approximately one wavelength of visible light.
  • Optical path length is the distance light travels multiplied by the refractive index of the medium.
  • Interference in wedge-shaped thin films results in straight, parallel, and equidistant fringes.
  • Newton's rings are an interference phenomenon observed when light is reflected from a plano-convex lens and a plane glass plate.
  • The rings are concentric and exhibit alternating bright and dark bands.
  • The radius of rings depends on the order of the ring and the curvature of the lens.

Thin Film Interference

  • Thin film interference occurs when light reflects from the top and bottom surfaces of a thin film, and those reflected waves interfere with each other.
  • The interference patterns depend on the thickness of the film, the refractive index of the film, and the wavelength of the light.
  • Anti-reflection coatings use thin films to minimize reflection by creating destructive interference between reflected waves.

Applications

  • Interference is used to test the flatness of optical surfaces.
  • Anti-reflection coatings are used in optical instruments (telescopes, cameras) to reduce light loss due to reflections.
  • Interference filters are used to isolate specific wavelengths of light.

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Wave Optics Notes PDF

Description

Test your knowledge on wave optics concepts including interference, diffraction, and the behavior of light. This quiz covers key phenomena such as constructive interference, superposition, and the relationship between wavelengths and light patterns. Evaluate your understanding of how optical principles apply to modern technologies like computer chips.

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