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Refractive Index

Sally Lancaster 13 questions

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Questions in this quiz (13)

  1. 1Refraction is the way a wave changes [blank_start]direction[blank_end] as it enters a different [blank_start]medium[blank_end]. The change in direction is a result of the wave [blank_start]slowing[blank_end] down or speeding [blank_start]up[blank_end]. When this happens, the wave will [blank_start]bend[blank_end] towards or away from the [blank_start]normal[blank_end].
    - If a light ray bends towards the normal, it is [blank_start]slowing[blank_end] [blank_start]down[blank_end]. The ray is going from a [blank_start]less[blank_end] optically dense material to a [blank_start]more[blank_end] optically dense material.
    - If the ray bends away from the normal, the wave is [blank_start]speeding[blank_end] [blank_start]up[blank_end]. It is going from an optically [blank_start]denser[blank_end] material to a [blank_start]less[blank_end] optically dense material.
    - The speed changes because the [blank_start]wavelength[blank_end] of the wave is changing and the [blank_start]frequency[blank_end] stays constant (v = fλ).
    - If light travels from a less optically dense material to a more optically dense material, the wave [blank_start]slows[blank_end] [blank_start]down[blank_end], the wavelength [blank_start]decreases[blank_end] and the [blank_start]frequency[blank_end] stays the same.    Image for question 1
    1. Adirection
    2. Bmedium
    3. Cslowing
    4. Dup
    5. Ebend
    6. Fnormal
    7. Gslowing
    8. Hdown
    9. Ispeeding
    10. Jless
    11. Kup
    12. Lmore
    13. Mless
    14. Ndenser
    15. Owavelength
    16. Pfrequency
    17. Qslows
    18. Rdown
    19. Sdecreases
    20. Tfrequency
  2. 2Light goes fastest in a [blank_start]vacuum[blank_end]. It [blank_start]slows down[blank_end] in other materials because it interacts with the [blank_start]particles[blank_end] in them.
    The more optically dense a material is, the [blank_start]more[blank_end] light slows down when it enters it and hence the [blank_start]higher[blank_end] the refractive index.
    The refractive index of a material, n, is the [blank_start]ratio[blank_end] between the speed of light in a vacuum, [blank_start]c[blank_end], and the speed of light in that material, [blank_start]v[blank_end].
    n = [blank_start]c / v[blank_end] where c = 3.00 x 10^8 ms^-1
    The speed of light in air is only a [blank_start]tiny[blank_end] bit smaller than c. Therefore you [blank_start]can[blank_end] assume the refractive index of air is [blank_start]1[blank_end].
    1. Avacuum
    2. Bslows down
    3. Cspeeds up
    4. Dparticles
    5. Emore
    6. Fless
    7. Ghigher
    8. Hlower
    9. Iratio
    10. Jc / v
    11. Kv / c
    12. Lv
    13. Mc
    14. Ntiny
    15. Ocan
    16. Pcan't
    17. Q1
  3. 3Snell's Law:
    1. The angle the incoming light makes to the normal is called the angle of [blank_start]incidence[blank_end], θ1.
    The angle the refracted ray makes with the normal is called the angle of [blank_start]refraction[blank_end], θ2.
    2. The light is crossing a boundary, going from a medium with [blank_start]refractive[blank_end] [blank_start]index[blank_end] n1 to a medium with refractive index [blank_start]n2[blank_end].
    3. When light enters an optically denser medium it is refracted [blank_start]towards[blank_end] the normal.
    4. n1, n2, θ1 and θ2 are related by Snell's law: n1sinθ[blank_start]1[blank_end] = n2[blank_start]sin[blank_end]θ2    Image for question 3
    1. Aincidence
    2. Brefraction
    3. Crefractive
    4. Dindex
    5. En2
    6. Ftowards
    7. G1
    8. Hsin
  4. 4Critical Angle:
    When light goes from an optically dense material into an optically [blank_start]less[blank_end] dense material (e.g. glass to air), interesting things can start to happen. As you increase the angle of [blank_start]incidence[blank_end], the angle of refraction gets closer and closer to [blank_start]90[blank_end]°. Eventually the angle of incidence, θ1 reaches a [blank_start]critical[blank_end] angle C for which the angle of [blank_start]refraction[blank_end] θ2 = [blank_start]90[blank_end]°. The light is refracted [blank_start]along[blank_end] the boundary.
    At angles of incidence [blank_start]greater[blank_end] than C, refraction is impossible. That means [blank_start]all[blank_end] the light is [blank_start]reflected[blank_end] back into the material. This effect is called [blank_start]total[blank_end] [blank_start]internal[blank_end] [blank_start]reflection[blank_end].
    For light hitting a material-to-air boundary (assuming the material is [blank_start]more[blank_end] optically dense) at the [blank_start]critical[blank_end] angle, Snell's law simplifies to become: [blank_start]sinC[blank_end] = [blank_start]1[blank_end] / [blank_start]n[blank_end] where n is the refractive index of the [blank_start]material[blank_end] (n[blank_start]1[blank_end] below)
    This happens because n2 = air = [blank_start]1[blank_end], sinθ[blank_start]2[blank_end] = sin(90°) = 1 and θ1 = [blank_start]C[blank_end]. n1sinθ1 = n2sinθ2    Image for question 4
    1. Aless
    2. B90
    3. Cincidence
    4. Dcritical
    5. Erefraction
    6. F90
    7. Galong
    8. Hgreater
    9. Iall
    10. Jreflected
    11. Ktotal
    12. Linternal
    13. Mreflection
    14. Nmore
    15. Ocritical
    16. PsinC
    17. Q1
    18. Rn
    19. Smaterial
    20. T1
    21. U1
    22. V2
    23. WC
  5. 5Investigating Critical Angles and Total Internal Reflection:
    1. Shine a light ray into the [blank_start]curved[blank_end] face of a semi-circular glass block so that it always enters at [blank_start]right angles[blank_end] to the edge - this means the ray won't [blank_start]refract[blank_end] as it enters the block, just when it leaves from the straight edge.
    2. Vary the angle of [blank_start]incidence[blank_end], i, until the light beam refracts so much that it exits the block along the [blank_start]straight edge[blank_end]. This angle of incidence is the [blank_start]critical angle[blank_end], C, for [blank_start]glass-air[blank_end] boundary.
    3. Use n = 1 / sinC to find the [blank_start]refractive index[blank_end] of the block if you want.
    4. If you increase the angle of incidence so it's [blank_start]greater[blank_end] than C, you'll find the ray is [blank_start]reflected[blank_end] from the straight edge of the block.
    θ < C means a refracted ray and a [blank_start]partially[blank_end] reflected ray
    θ = C means a refracted ray along the boundary (90°) and a [blank_start]stronger[blank_end] reflected ray
    θ > C means total internal reflection (no refraction and [blank_start]strongest[blank_end] reflected ray)
    Image for question 5
    1. Acurved
    2. Bright angles
    3. Crefract
    4. Dreflect
    5. Eincidence
    6. Fstraight edge
    7. Gcritical angle
    8. Hglass-air
    9. Iair-glass
    10. Jrefractive index
    11. Kgreater
    12. Lless
    13. Mreflected
    14. Nrefracted
    15. Opartially
    16. Pstronger
    17. Qstrongest
  6. 6Velocity in Medium, v:Image for question 6
    1. AThe lower the refractive index of the medium, the faster light will travel in it.
    2. BThe higher the refractive index of the medium, the faster light will travel in it.
    3. CAs temperature increases, density of air decreases. Therefore speed of light increases because as the atoms get further apart it becomes more like a vacuum where light travels fastest.
    4. DAs temperature increases, density of air decreases. Therefore speed of light decreases because as the atoms get further apart it becomes more like a vacuum where light travels fastest.
    5. EIf light travels faster in hotter air, the refractive index of air decreases (n air = c / v air).
    6. FIf light travels faster in hotter air, the refractive index of air increases (n air = c / v air).
    7. GA mirage is caused by this change in n air as the air temperature changes (light travels faster in the hotter, less dense air with a lower refractive index).
  7. 7Red and Violet Light:Image for question 7
    1. ARed light has the higher speed in glass because it bends the least so slows down the least and refracts the least.
    2. BRed light and violet light travel at the same speed in a vacuum because all colours of light travel at the same speed in a vacuum (3.00 x 10^8).
    3. Cn violet in glass is higher than n red in glass because violet light bends more so slows down more and refracts more (n = c / v).
    4. DViolet light has the higher speed in glass because it bends the least so slows down the least and refracts the least.
    5. ERed light and violet light travel at different speeds in a vacuum because all colours of light travel at different speeds in a vacuum.
    6. Fn violet in glass is lower than n red in glass because violet light bends more so slows down more and refracts more (n = c / v).
  8. 8Reflection and Diagrams:
    - Angle of incidence = Angle of [blank_start]reflection[blank_end]
    - Rays of light are drawn at [blank_start]90[blank_end]° to the [blank_start]wavefronts[blank_end] for plan view diagrams.
    - The n[blank_start]ormal[blank_end] is at 90° to the boundary.
    Image for question 8
    1. Areflection
    2. B90
    3. Cwavefronts
    4. Dormal
  9. 9Water Waves and Refraction:
    - Water waves in deep water have a [blank_start]longer[blank_end] wavelength so travel [blank_start]faster[blank_end] for constant frequency.
    - Water waves in shallower water have a [blank_start]shorter[blank_end] wavelength so travel [blank_start]slower[blank_end] for constant frequency.
    - At a deep-shallow boundary, the water waves will bend [blank_start]towards[blank_end] the normal as their wavelength [blank_start]decreases[blank_end] and they [blank_start]slow down[blank_end] (frequency remains constant).    Image for question 9
    1. Alonger
    2. Bshorter
    3. Cfaster
    4. Dslower
    5. Eshorter
    6. Flonger
    7. Gslower
    8. Hfaster
    9. Itowards
    10. Jaway from
    11. Kdecreases
    12. Lincreases
    13. Mslow down
    14. Nspeed up
  10. 10Optical Fibres:
    Optical fibres use [blank_start]total[blank_end] [blank_start]internal[blank_end] [blank_start]reflection[blank_end].
    It is essential that the light ray hits the c[blank_start]ore[blank_end]-c[blank_start]ladding[blank_end] boundary at an angle [blank_start]greater[blank_end] than the critical angle for them to work (i.e. for the light to totally internally reflect).
    The cladding must also be of a [blank_start]lower[blank_end] refractive index than the core and the light ray must start in the [blank_start]core[blank_end] so that it is going from a [blank_start]more[blank_end] dense material to a [blank_start]less[blank_end] dense material.    Image for question 10
    1. Atotal
    2. Binternal
    3. Creflection
    4. Dgreater
    5. Eore
    6. Fladding
    7. Glower
    8. Hcore
    9. Imore
    10. Jless

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Description
AS - Level Sally's Physics (Waves and Particle Nature of Light) Quiz on Refractive Index, created by Sally Lancaster on 19/04/2016.
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