1918638
Descripción
Pregunta 1
Pregunta
According to Stokes shift, if λ is the wavelength of stimulating radiation and λ2 - of the emitted luminescence radiation, then:
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λ1 < λ2;
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λ1 > λ2
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λ1 = λ2
Pregunta 2
Pregunta
Quantum yield (Wavilov's law) is defined as:
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(Number of emission photons) / (Number of excitation photons)
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(Number of excitation photons) / (Number of emission photons)
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(Number of emitted photons) / (Number of excitation photons)
Pregunta 3
Pregunta
Phosphorescence is when an electron has returned to singlet (basic) level, passing through an intermediate level that is:
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Singlet
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Triplet (metastable)
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Energy level higher than ground level.
Pregunta 4
Pregunta
The following statement: "Under the influence of a photon with suitable energy, the electron returns to singlet state from the metastable level" describes:
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Emission of white light
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Stimulated emission
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Infrared emission with SoLux (Incandescent lamp used in physical therapy)
Pregunta 5
Pregunta
The active medium of a laser must have:
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Short half-life t1/2 of exited states:
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Acoustic impedance Za matching that of target tissues
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The possibility for population inversion
Pregunta 6
Pregunta
Light is monochromatic when:
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It is a single wavelength λ
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It propagates in the same direction
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It propagates in-phase
Pregunta 7
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The output mirror of laser resonator is:
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Semi-transparent
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Completely transparent
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Non-transparent (opaque)
Pregunta 8
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The laser can be:
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A flux of protons
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A flux of electrons with the same energy
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An electromagnetic radiation with specific properties
Pregunta 9
Pregunta
The laser is:
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Radionuclide generator for generating metastable radionuclide 99m Tc
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Generator of light with specific properties
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Ultrasound generator
Pregunta 10
Pregunta
Light generation in a laser is a result of:
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Spontaneous electron transitions
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Stimulated electron transitions
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Spontaneous and stimulated transitions of electrons
Pregunta 11
Pregunta
Separation of tissue fragments with a laser, without causing necrosis to underlying cells is called:
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Denaturation of proteins
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Coagulation
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Photoablation
Pregunta 12
Pregunta
Electromagnetic waves are coherent when:
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They oscillate with the same frequency, and with constant phase difference.
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They have the same wavelength λ
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They propagate in the same plane.
Pregunta 13
Pregunta
What is the definition for population inversion?
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More electrons occupy high energy levels than lower energy levels
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Fewer electrons occupy high energy levels than lower energy levels
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There are vacant electron energy levels.
Pregunta 14
Pregunta
Laser radiation DOES NOT have the properties of:
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Coherence and polarization
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Emission in the visible spectrum only
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Collimation (Directionality)
Pregunta 15
Pregunta
What properties summarize laser light the best:
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Monochromatic, Coherent, Collimated
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Polychromatic, Polarized, Collimated
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Monochromatic, Coherent, Diffracted
Pregunta 16
Pregunta
Lasers produce light with specific properties through:
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Spontaneous emission
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Stimulated emission
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Fluorescence
Pregunta 17
Pregunta
Laser endoscopes are preferred to light endoscopes. Which of the statements below is NOT a factor for this choice:
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They can eliminate infrared light from the emission spectrum (through a suitable choice of gain medium)
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They provide optimal illumination of examined organs
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Examination is more comfortable for the patient
Pregunta 18
Pregunta
PDT of endobronchial cancer uses a laser of 630 nm wavelength. In what of the range is this emission:
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UV Range
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IR Range
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Visible Range
Pregunta 19
Pregunta
In photo-dynamic therapy (PDT), excitation wavelength is specific to the photo-sensitizing drug used. What type of laser light is suitable for HpD photosensitizer with 410 nm emission:
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λ = 390 nm
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λ = 500 nm
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λ = 630 nm
Pregunta 20
Pregunta
Photodynamic therapy of mild jaundice in babies (elevated bilirubin causes yellow skin pigmentation) turns bilirubin into more soluble form, easier to excrete from the body. What type of laser light is most suitable for skin treatment:
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Red
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Orange
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Blue
Pregunta 21
Pregunta
In photo-dynamic therapy, malignant tissue is selectively destroyed by a combination of:
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Photosensitizing drug (photosensitizer) and the presence of oxygen
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Photosensitizer, sunlight and oxygen
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Photosensitizer and laser light
Pregunta 22
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Photodynamic therapy based on:
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Existent singlet oxygen (1 O2) in cancer tissues
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Singlet oxygen (1 O2) generation upon irradiation
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Molecular oxygen (O2) generation upon irradiation
Pregunta 23
Pregunta
In a optical microscope the object is located at a distance
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Less than the focal length of the objective lens
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More than the focal length but less than double the focal length of objective
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Exactly at the focal length of the objective lens
Pregunta 24
Pregunta
In an optical microscope, where is the object located with respect to the eyepiece lens:
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Less than the focal distance of the eyepiece
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Further than the focal distance, but less than double the focal distance of the eyepiece
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At the focal distance of the eyepiece lens
Pregunta 25
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The image formed by the microscope lens is:
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Real
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Virtual
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Real and Reduced
Pregunta 26
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The image formed by the microscope eyepiece is:
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Real
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Virtual
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Real and Reduced
Pregunta 27
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The image formed by a compound microscope is:
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Real, Magnified and Reversed
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Real, Magnified and Erect (upright)
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Virtual, Magnified and Reversed
Pregunta 28
Pregunta
What feature of the human eye limits the maximum magnification of optical microscope:
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The Optic Power
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The Resolution
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The Spectral Sensitivity
Pregunta 29
Pregunta
A negative magnification always means that the image is:
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Erect
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Real
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Virtual
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Inverted
Pregunta 30
Pregunta
UV microscopes do not have any significant applications in medicine despite their maximum useful magnification which is about 2 times higher than that of the conventional microscope because:
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The image cannot be directly observed with the eyes
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UV rays are dangerous
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No powerful sources of UV light exist
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UV rays change the objects under examination.
Pregunta 31
Pregunta
After passing through a convex lens, rays of light traveling parallel to the axis, will be refracted to the lens:
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Center
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Principle focus
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Remain parallel
Pregunta 32
Pregunta
When an object is located at distance greater than two focal lengths in front of a converging lens, the image will be:
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Real and Enlarged
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Virtual and Enlarged
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Real and Reduced
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Virtual
Pregunta 33
Pregunta
Virtual images formed by converging lenses would appear:
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Bigger
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The Same Size
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Smaller
Pregunta 34
Pregunta
What wave phenomenon allows the existence of optical microscopes:
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Diffraction
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Refraction
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Interference
Pregunta 35
Pregunta
In an optical microscope, Wavelength of light is changed from 550 nm to 450 nm. The numerical aperture (NA) stays the same same. The resolution will:
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Get better
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Get worse
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Stay the same
Pregunta 36
Pregunta
Electron microscopes have better resolution than light microscopes. This is because:
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Electrons are faster than light
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Electrons have more energy than light
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Electrons have shorter wavelengths than light
Pregunta 37
Pregunta
Electron microscopes use special lenses such as:
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Optical Lenses with high index of refraction
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Optical Lenses with low index of refraction
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Magnetic lenses
Pregunta 38
Pregunta
The human eye is most sensitive to:
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Blue light
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Green light
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Red light
Pregunta 39
Pregunta
Which wavelength λ is not perceived by the human eye:
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500 nm
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1000 nm
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620 nm
Pregunta 40
Pregunta
The optical power of the human eye is approximately equal to:
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0.5 dpt
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7 dpt
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17 dpt
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70 dpt
Pregunta 41
Pregunta
2/3 of human eyes optical power is due to the air-cornea interface. This is because:
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Refractive indices of air and cornea have greater difference, compared to other refractive surfaces in the eye.
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The cornea has the largest curvature
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The cornea is thicker than the lens
Pregunta 42
Pregunta
The image formed on the retina of the human eye is at a distance:
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Greater than the double focal length of the eye's lens
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Equal to the double focal length of the eye's lens
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Less than the double focal length of the eye's lens
Pregunta 43
Pregunta
The image formed on the retina is:
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Real, Enlarged and Inverted
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Real, Reduced and Inverted
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Real, Reduced and Erect
Pregunta 44
Pregunta
Nature has deprived human eyes from IR vision, which some animals poses. Is this expedient:
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No. Human optical receptors are less adept.
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No. Humans cannot hunt at night.
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Yes, The eye is a powerful source of IR and will be blinded by self emission.
Pregunta 45
Pregunta
Can you tell by looking at a person's eyes and spectacles, if they have myopia or hyperopia? Which of the statements below is not correct?
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Myopic eyes look semi-closed and hyperopic eyes look wide open
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Myopic lenses have thicker periphery, hyperopic have thicker center part
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Pupils of myopic eyes look small and pupils of hyperopic eyes look enlarged.
Pregunta 46
Pregunta
Which human organ is "responsible" for inter-eye coordination:
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The thyroid gland
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The vestibular apparatus
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The brain
Pregunta 47
Pregunta
Astigmatism is due to:
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Non-uniform curvature of eye lens:
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Lack of coincidence of eye's anatomical and optical exes
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Non-uniform curvature of the cornea
Pregunta 48
Pregunta
The stroboscopic effect is due to:
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The ability of the optical receptor to retain images for certain time
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The ability of the optical receptor to determine the distances by eye (the so called estimation by sight)
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The volumetric (three-dimensional) vision.
Pregunta 49
Pregunta
What type of lenses are used for correction of myopia (short-sightedness)
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Cylindrical
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Spherical, Diverging
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Spherical, Converging
Pregunta 50
Pregunta
What type of lenses are used for correction of hypermetropia (far-sightness)
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Spherical, Diverging
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Spherical, Converging
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Cylindrical
Pregunta 51
Pregunta
What type of lenses are used for correction of astigmatism:
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Sphero-cylindrical
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Cylindrical
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Spherical, Diverging
Pregunta 52
Pregunta
Snell's window is an underwater phenomenon where a submerged observer looking up could see the entire hemisphere, horizon to horizon. In this case, a 180 degree view above water is compressed into a 97 degree angle under water (Figure 10, not included). This is possible because:
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Fish eyes are rounder than human eyes
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The water surface is curved
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Sound travels faster in water than in air
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Light travels faster in air then in water
Pregunta 53
Pregunta
Fish eyes are remarkably similar to human eyes. One significant different is the shape of crystalline lens. In fish they are denser and more spherical. This adaptation can be contributed to:
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The higher pressure underwater
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The speed of light in water
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The need to collect light from wider angles
Pregunta 54
Pregunta
The following can be described as refractive disorders of the eye:
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Myopia, Hyperopia, Strabismus
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Myopia, Hyperopia, Astigmatism
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Myopia, Presbyopia, Colour blindness
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Answers A + B
Pregunta 55
Pregunta
Underwater vision (for humans) is blurry. The focusing power of the cornea is greatly reduced when in contact with water. Why is that? :
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Because of additional pressure from water molecules
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Index of refraction of water is greater than index of refraction of air.
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Index of refraction of water is similar to the index of refraction of the cornea.
Pregunta 56
Pregunta
Which statement describes correctly the photoreceptor cells of the retina
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Cones have better sensitivity but lower resolution than rods
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Rods have better sensitivity but a lower count then cones
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Cones have higher resolution but lower sensitivity than rods.
Pregunta 57
Pregunta
There are three types of colour sensitive cone cells in the retina. Two types overlap significantly in their spectral sensitivity and one does not overlap much with the other two. Which are the two overlapping colours?
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Blue and green
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Red and blue
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Green and Red
Pregunta 58
Pregunta
Human eyes are the most sensitive to green light at 550 nm wavelength. What is the best explanation for this adaption:
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Green light is between the red and the blue
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Green light is usually brighter than red
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Green light from the sun arrives in greater intensity.
Pregunta 59
Pregunta
In addition to their eyes, Rattlesnakes have a pair of sensory organs called "Pits". Pits have a short range and are used mostly in night hunting. What type of waves can pits detect?
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Ultrasound
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Ultraviolet
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Infrasound
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Infrared
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