Quiz
PMU - Year 1 Physics - Part 3(B)
Questions in this quiz (59)
1According to Stokes shift, if λ is the wavelength of stimulating radiation and λ2 - of the emitted luminescence radiation, then:
- Aλ1 < λ2;
- Bλ1 > λ2
- Cλ1 = λ2
2Quantum yield (Wavilov's law) is defined as:
- A(Number of emission photons) / (Number of excitation photons)
- B(Number of excitation photons) / (Number of emission photons)
- C(Number of emitted photons) / (Number of excitation photons)
3Phosphorescence is when an electron has returned to singlet (basic) level, passing through an intermediate level that is:
- ASinglet
- BTriplet (metastable)
- CEnergy level higher than ground level.
4The following statement: "Under the influence of a photon with suitable energy, the electron returns to singlet state from the metastable level" describes:
- AEmission of white light
- BStimulated emission
- CInfrared emission with SoLux (Incandescent lamp used in physical therapy)
5The active medium of a laser must have:
- AShort half-life t1/2 of exited states:
- BAcoustic impedance Za matching that of target tissues
- CThe possibility for population inversion
6Light is monochromatic when:
- AIt is a single wavelength λ
- BIt propagates in the same direction
- CIt propagates in-phase
7The output mirror of laser resonator is:
- ASemi-transparent
- BCompletely transparent
- CNon-transparent (opaque)
8The laser can be:
- AA flux of protons
- BA flux of electrons with the same energy
- CAn electromagnetic radiation with specific properties
9The laser is:
- ARadionuclide generator for generating metastable radionuclide 99m Tc
- BGenerator of light with specific properties
- CUltrasound generator
10Light generation in a laser is a result of:
- ASpontaneous electron transitions
- BStimulated electron transitions
- CSpontaneous and stimulated transitions of electrons
11Separation of tissue fragments with a laser, without causing necrosis to underlying cells is called:
- ADenaturation of proteins
- BCoagulation
- CPhotoablation
12Electromagnetic waves are coherent when:
- AThey oscillate with the same frequency, and with constant phase difference.
- BThey have the same wavelength λ
- CThey propagate in the same plane.
13What is the definition for population inversion?
- AMore electrons occupy high energy levels than lower energy levels
- BFewer electrons occupy high energy levels than lower energy levels
- CThere are vacant electron energy levels.
14Laser radiation DOES NOT have the properties of:
- ACoherence and polarization
- BEmission in the visible spectrum only
- CCollimation (Directionality)
15What properties summarize laser light the best:
- AMonochromatic, Coherent, Collimated
- BPolychromatic, Polarized, Collimated
- CMonochromatic, Coherent, Diffracted
16Lasers produce light with specific properties through:
- ASpontaneous emission
- BStimulated emission
- CFluorescence
17Laser endoscopes are preferred to light endoscopes. Which of the statements below is NOT a factor for this choice:
- AThey can eliminate infrared light from the emission spectrum (through a suitable choice of gain medium)
- BThey provide optimal illumination of examined organs
- CExamination is more comfortable for the patient
18PDT of endobronchial cancer uses a laser of 630 nm wavelength. In what of the range is this emission:
- AUV Range
- BIR Range
- CVisible Range
19In 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:
- Aλ = 390 nm
- Bλ = 500 nm
- Cλ = 630 nm
20Photodynamic 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:
- ARed
- BOrange
- CBlue
21In photo-dynamic therapy, malignant tissue is selectively destroyed by a combination of:
- APhotosensitizing drug (photosensitizer) and the presence of oxygen
- BPhotosensitizer, sunlight and oxygen
- CPhotosensitizer and laser light
22Photodynamic therapy based on:
- AExistent singlet oxygen (1 O2) in cancer tissues
- BSinglet oxygen (1 O2) generation upon irradiation
- CMolecular oxygen (O2) generation upon irradiation
23In a optical microscope the object is located at a distance
- ALess than the focal length of the objective lens
- BMore than the focal length but less than double the focal length of objective
- CExactly at the focal length of the objective lens
24In an optical microscope, where is the object located with respect to the eyepiece lens:
- ALess than the focal distance of the eyepiece
- BFurther than the focal distance, but less than double the focal distance of the eyepiece
- CAt the focal distance of the eyepiece lens
25The image formed by the microscope lens is:
- AReal
- BVirtual
- CReal and Reduced
26The image formed by the microscope eyepiece is:
- AReal
- BVirtual
- CReal and Reduced
27The image formed by a compound microscope is:
- AReal, Magnified and Reversed
- BReal, Magnified and Erect (upright)
- CVirtual, Magnified and Reversed
28What feature of the human eye limits the maximum magnification of optical microscope:
- AThe Optic Power
- BThe Resolution
- CThe Spectral Sensitivity
29A negative magnification always means that the image is:
- AErect
- BReal
- CVirtual
- DInverted
30UV 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:
- AThe image cannot be directly observed with the eyes
- BUV rays are dangerous
- CNo powerful sources of UV light exist
- DUV rays change the objects under examination.
31After passing through a convex lens, rays of light traveling parallel to the axis, will be refracted to the lens:
- ACenter
- BPrinciple focus
- CRemain parallel
32When an object is located at distance greater than two focal lengths in front of a converging lens, the image will be:
- AReal and Enlarged
- BVirtual and Enlarged
- CReal and Reduced
- DVirtual
33Virtual images formed by converging lenses would appear:
- ABigger
- BThe Same Size
- CSmaller
34What wave phenomenon allows the existence of optical microscopes:
- ADiffraction
- BRefraction
- CInterference
35In 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:
- AGet better
- BGet worse
- CStay the same
36Electron microscopes have better resolution than light microscopes. This is because:
- AElectrons are faster than light
- BElectrons have more energy than light
- CElectrons have shorter wavelengths than light
37Electron microscopes use special lenses such as:
- AOptical Lenses with high index of refraction
- BOptical Lenses with low index of refraction
- CMagnetic lenses
38The human eye is most sensitive to:
- ABlue light
- BGreen light
- CRed light
39Which wavelength λ is not perceived by the human eye:
- A500 nm
- B1000 nm
- C620 nm
40The optical power of the human eye is approximately equal to:
- A0.5 dpt
- B7 dpt
- C17 dpt
- D70 dpt
412/3 of human eyes optical power is due to the air-cornea interface. This is because:
- ARefractive indices of air and cornea have greater difference, compared to other refractive surfaces in the eye.
- BThe cornea has the largest curvature
- CThe cornea is thicker than the lens
42The image formed on the retina of the human eye is at a distance:
- AGreater than the double focal length of the eye's lens
- BEqual to the double focal length of the eye's lens
- CLess than the double focal length of the eye's lens
43The image formed on the retina is:
- AReal, Enlarged and Inverted
- BReal, Reduced and Inverted
- CReal, Reduced and Erect
44Nature has deprived human eyes from IR vision, which some animals poses. Is this expedient:
- ANo. Human optical receptors are less adept.
- BNo. Humans cannot hunt at night.
- CYes, The eye is a powerful source of IR and will be blinded by self emission.
45Can 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?
- AMyopic eyes look semi-closed and hyperopic eyes look wide open
- BMyopic lenses have thicker periphery, hyperopic have thicker center part
- CPupils of myopic eyes look small and pupils of hyperopic eyes look enlarged.
46Which human organ is "responsible" for inter-eye coordination:
- AThe thyroid gland
- BThe vestibular apparatus
- CThe brain
47Astigmatism is due to:
- ANon-uniform curvature of eye lens:
- BLack of coincidence of eye's anatomical and optical exes
- CNon-uniform curvature of the cornea
48The stroboscopic effect is due to:
- AThe ability of the optical receptor to retain images for certain time
- BThe ability of the optical receptor to determine the distances by eye (the so called estimation by sight)
- CThe volumetric (three-dimensional) vision.
49What type of lenses are used for correction of myopia (short-sightedness)
- ACylindrical
- BSpherical, Diverging
- CSpherical, Converging
50What type of lenses are used for correction of hypermetropia (far-sightness)
- ASpherical, Diverging
- BSpherical, Converging
- CCylindrical
51What type of lenses are used for correction of astigmatism:
- ASphero-cylindrical
- BCylindrical
- CSpherical, Diverging
52Snell'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:
- AFish eyes are rounder than human eyes
- BThe water surface is curved
- CSound travels faster in water than in air
- DLight travels faster in air then in water
53Fish 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:
- AThe higher pressure underwater
- BThe speed of light in water
- CThe need to collect light from wider angles
54The following can be described as refractive disorders of the eye:
- AMyopia, Hyperopia, Strabismus
- BMyopia, Hyperopia, Astigmatism
- CMyopia, Presbyopia, Colour blindness
- DAnswers A + B
55Underwater vision (for humans) is blurry. The focusing power of the cornea is greatly reduced when in contact with water. Why is that? :
- ABecause of additional pressure from water molecules
- BIndex of refraction of water is greater than index of refraction of air.
- CIndex of refraction of water is similar to the index of refraction of the cornea.
56Which statement describes correctly the photoreceptor cells of the retina
- ACones have better sensitivity but lower resolution than rods
- BRods have better sensitivity but a lower count then cones
- CCones have higher resolution but lower sensitivity than rods.
57There 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?
- ABlue and green
- BRed and blue
- CGreen and Red
58Human eyes are the most sensitive to green light at 550 nm wavelength. What is the best explanation for this adaption:
- AGreen light is between the red and the blue
- BGreen light is usually brighter than red
- CGreen light from the sun arrives in greater intensity.
59In 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?
- AUltrasound
- BUltraviolet
- CInfrasound
- DInfrared
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- All Questions uploaded word for word from MCQ book. All Credit to Authors. Mistakes due in process may have been made, use and check your work at your own discretion. Only simple writing allowed, i.e Superscript and Subscript absent. Questions missed due to Figure/Diagrams/Text: 69.89.90.106.
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