Polarization and Double Refraction Concepts
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Polarization and Double Refraction Concepts

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Questions and Answers

What happens to the ordinary and extraordinary waves at normal incidence in a crystal?

  • They interfere destructively, canceling each other out.
  • They travel in parallel directions with different velocities. (correct)
  • They separate into two distinct beams.
  • They merge into a single beam with no path difference.

    • Which equation represents the extraordinary ray's amplitude in terms of the incident amplitude and phase difference?

  • x = A sin(𝜃) sin(ωt)
  • x = A cos(𝜃) sin(ωt)
  • x = A cos(𝜃) sin(ωt + δ) (correct)
  • x = A sin(𝜃) sin(ωt + δ)

    • How is the amplitude of the ordinary ray expressed in the content?

  • A cos(θ) cos(ωt)
  • A cos(𝜃) sin(ωt + δ)
  • A sin(𝜃) sin(ωt) (correct)
  • A sin(θ) cos(ωt)

    • What is the relationship between x and y based on the equations provided?

    <p>x/y = cos(δ) + √(1 - y2/b2)</p> Signup and view all the answers

    What effect does the angle θ have on the amplitudes of the ordinary and extraordinary rays?

    <p>It determines both amplitudes, introducing a phase difference.</p> Signup and view all the answers

    In the derived equations for x and y, what represents the phase difference?

    <p>δ</p> Signup and view all the answers

    What characteristic of polarized light is utilized in quarter wave and half wave plates?

    <p>The different velocities and phase shifts of the ordinary and extraordinary rays.</p> Signup and view all the answers

    What is denoted as A in the context of the incident plane polarized light?

    <p>The amplitude of the incident plane polarized light.</p> Signup and view all the answers

    What is 'unpolarised light' characterized by?

    <p>Vibrations in all directions</p> Signup and view all the answers

    Which method of polarization involves Malus's discovery?

    <p>Polarisation by reflection</p> Signup and view all the answers

    What happens to unpolarised light when it passes through crystal A?

    <p>Only vibrations parallel to the crystal's axis are transmitted</p> Signup and view all the answers

    When unpolarised light passes through a series of thin glass plates, what percentage of vibrations typically reflects?

    <p>15%</p> Signup and view all the answers

    What is indicated by the term 'ordinary ray' in double refraction?

    <p>The ray that vibrates in a plane parallel to the crystal axis</p> Signup and view all the answers

    In the context of polarization, what is the 'plane of vibration'?

    <p>The direction of all polarized vibrations</p> Signup and view all the answers

    Which of the following methods does not lead to polarization?

    <p>Scattering</p> Signup and view all the answers

    What is the result of polarization by double refraction?

    <p>Two refracted rays are produced that are orthogonal</p> Signup and view all the answers

    What does the tangent plane CO represent in the context of the O-ray?

    <p>Position of the O-wave front</p> Signup and view all the answers

    Which equation represents the relationship between the velocities of the ordinary ray and extraordinary ray?

    <p>$V_e = \frac{V_a}{\mu_e}$</p> Signup and view all the answers

    What occurs when O and E waves coincide at all instants under normal incidence?

    <p>There is no double refraction</p> Signup and view all the answers

    In the case where the optic axis is perpendicular to the refracting surface, what happens during oblique incidence?

    <p>The two wave fronts touch at a point</p> Signup and view all the answers

    What direction does the line AP represent in the oblique incidence scenario?

    <p>Direction of the optic axis</p> Signup and view all the answers

    How do the O and E rays behave in the case where the optic axis is parallel to the refracting face under oblique incidence?

    <p>They travel with different velocities along different directions</p> Signup and view all the answers

    Which plane represents the wave front of the E waves intersecting at point E?

    <p>Plane CE</p> Signup and view all the answers

    What is indicated by the tangent planes OOl and EEl in normal incidence?

    <p>They represent the wave fronts of O and E rays respectively</p> Signup and view all the answers

    What does a beam passing through a quarter wave plate and subsequently an N-prism indicate if it extinguishes completely twice during rotation?

    <p>The beam is circularly polarized.</p> Signup and view all the answers

    What is the characteristic behavior of elliptically polarized light when passed through a rotating N-prism?

    <p>Its intensity varies from maximum to minimum.</p> Signup and view all the answers

    What further phase difference do the O-ray and E-ray undergo when elliptically polarized light passes through a quarter wave plate?

    <p>$ rac{ ext{π}}{2}$</p> Signup and view all the answers

    What is the purpose of the Babinet's compensator?

    <p>To introduce a desired path difference for varying wavelengths.</p> Signup and view all the answers

    What condition should be avoided when light is incident on a QWP to ensure it emerges elliptically polarized?

    <p>At 45 degrees to the optic axis.</p> Signup and view all the answers

    After passing elliptically polarized light through a quarter wave plate, if the beam remains elliptically polarized, what does that imply?

    <p>The incident beam was partially polarized.</p> Signup and view all the answers

    How can you distinguish between circularly polarized light and unpolarized light after passing through a quarter wave plate?

    <p>Only circularly polarized light will extinguish completely upon rotation.</p> Signup and view all the answers

    In the context of light polarization, what indicates that a beam is partially polarized when observed through an N-prism?

    <p>The beam shows some variation in intensity.</p> Signup and view all the answers

    What is the least thickness of the quartz plate required for plane polarized light to emerge plane polarized?

    <p>2.778 × 10−5 m</p> Signup and view all the answers

    How is the thickness of a calcite plate for circularly polarized light calculated?

    <p>Using the difference of refractive indices and wavelength.</p> Signup and view all the answers

    What is the required thickness of a calcite plate to convert plane polarized light into circularly polarized light?

    <p>8.565 × 10−7 m</p> Signup and view all the answers

    What is the optical path difference produced by a crystal plate if the thickness is 1.5 × 10−5 m?

    <p>1.5 × 10−7 m</p> Signup and view all the answers

    For circularly polarized light, what is the formula for calculating the thickness of a plate?

    <p>t = λ / 4(μe − μ0)</p> Signup and view all the answers

    What is the rotation of the plane of polarization in a substance if the wavelength is 5890 × 10−10 m?

    <p>7.62 × 10−8</p> Signup and view all the answers

    Which of the following factors affects the optical path difference in a crystal plate?

    <p>All of the above</p> Signup and view all the answers

    What determines whether a light beam will become circularly polarized when passing through a material?

    <p>Both A and B</p> Signup and view all the answers

    What is the relationship between phase difference and path difference in a wave?

    <p>Phase difference is proportional to path difference.</p> Signup and view all the answers

    How is the wavelength calculated from phase difference and path difference?

    <p>Wavelength can be determined using the formula λ = t(μL - μR) / φ.</p> Signup and view all the answers

    When given a concentration of a solution and the length of the polarimeter tube, how is the rotation of the plane of polarization calculated?

    <p>Rotation is calculated as the product of specific rotation, length, and concentration.</p> Signup and view all the answers

    If a polarimeter tube produces an optical rotation of 240 with a specific rotation of S, what quantity is needed to determine S?

    <p>All of the above.</p> Signup and view all the answers

    What is the phase difference when the path difference is 5890 x 10-10 and the thickness of the material is 2m in given conditions?

    <p>0.8125 radians.</p> Signup and view all the answers

    In the case of a sugar solution with a concentration of 100 kgm-3, what does the specific rotation of the sugar represent?

    <p>The ratio of angle rotated to the concentration and length.</p> Signup and view all the answers

    When calculating the rotation of the plane of polarization in a polarimeter, what incorrectly describes the process?

    <p>The specific rotation has no impact on the measured rotation.</p> Signup and view all the answers

    If a solution has a specific rotation of 0.750 kg-1m2 and its concentration is given, what information would not change the calculation of the plane rotation?

    <p>Material the tube is made from.</p> Signup and view all the answers

    Study Notes

    Polarization of Light

    • Polarization is a property of waves, specifically light waves, indicating the direction of their oscillations
    • Light waves exhibit transverse nature, meaning vibrations are perpendicular to the direction of travel
    • Unpolarized light has vibrations in all directions, while polarized light has vibrations in a specific direction
    • Techniques for obtaining polarized light include reflection, refraction, double refraction, and selective absorption.

    Double Refraction in Uniaxial Crystals

    • Uniaxial crystals have one optic axis, a line along which no double refraction occurs
    • These crystals, like calcite and quartz, transmit light as two rays: ordinary (obeying Snell's law) and extraordinary (not obeying Snell's law)
    • The ordinary ray's speed is constant in all directions, while the extraordinary ray's speed varies with the direction relative to the optic axis
    • The direction along which no double refraction takes place is called optic axis.

    Positive and Negative Crystals

    • Positive crystals: The extraordinary ray travels slower than the ordinary ray
    • Negative crystals: The extraordinary ray travels faster than the ordinary ray

    Principal Refractive Indices

    • In uniaxial crystals, two principal refractive indices exist: one for the ordinary ray (μo) and one for the extraordinary ray (μe)
    • μo represents the refractive index for the ordinary ray, which is the same in all directions
    • μe represents the refractive index for the extraordinary ray, which varies with the direction relative to the optic axis

    Plane, Circularly, and Elliptically Polarized Light

    • Plane-polarized light vibrates in a single plane
    • Circularly-polarized light vibrates in a circle
    • Elliptically-polarized light vibrates in an ellipse

    Quarter-Wave Plate

    • Used to convert plane-polarized light into circularly-polarized light
    • Introduces a phase difference of π/2 between ordinary and extraordinary rays

    Half-Wave Plate

    • Used to convert plane-polarized light into plane-polarized light with the polarization plane rotated
    • Introduces a phase difference of π between ordinary and extraordinary rays

    Babinet Compensator

    • An optical device for producing and analyzing elliptically polarized light
    • Allows for the introduction of variable phase differences between ordinary and extraordinary rays

    Optical Activity

    • Certain substances (like sugar solutions) rotate the plane of polarization of light passing through them
    • Dextrorotatory substances rotate the plane of polarization clockwise, while levorotatory substances rotate the plane of polarization counterclockwise
    • Fresnal's explanation: optical rotation arises from the different speeds of right-handed and left-handed circularly polarized light

    Specific Rotation

    • A measure of the degree of optical rotation for a given substance
    • Depends on the length and concentration of the solution, the wavelength of light, and temperature

    Laurent's Half-shade Polarimeter

    • Used to measure the specific rotation of optically active substances
    • Uses a half-shade device to compensate for differences in light intensity, enabling precise measurements of rotation.

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    Polarisation PDF - B.Sc IV Sem Physics

    Description

    This quiz covers the principles of light polarization and the behavior of light in uniaxial crystals. Learn about the transverse nature of light waves, different methods of obtaining polarized light, and how uniaxial crystals like calcite and quartz exhibit double refraction. Test your understanding of these fundamental concepts in optics.

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