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PMU - Year 1 Physics - Part 3(B)

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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.
Sole C
Quiz by Sole C, updated more than 1 year ago
Sole C
Created by Sole C about 9 years ago
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Question 1

Question
According to Stokes shift, if λ is the wavelength of stimulating radiation and λ2 - of the emitted luminescence radiation, then:
Answer
  • λ1 < λ2;
  • λ1 > λ2
  • λ1 = λ2

Question 2

Question
Quantum yield (Wavilov's law) is defined as:
Answer
  • (Number of emission photons) / (Number of excitation photons)
  • (Number of excitation photons) / (Number of emission photons)
  • (Number of emitted photons) / (Number of excitation photons)

Question 3

Question
Phosphorescence is when an electron has returned to singlet (basic) level, passing through an intermediate level that is:
Answer
  • Singlet
  • Triplet (metastable)
  • Energy level higher than ground level.

Question 4

Question
The following statement: "Under the influence of a photon with suitable energy, the electron returns to singlet state from the metastable level" describes:
Answer
  • Emission of white light
  • Stimulated emission
  • Infrared emission with SoLux (Incandescent lamp used in physical therapy)

Question 5

Question
The active medium of a laser must have:
Answer
  • Short half-life t1/2 of exited states:
  • Acoustic impedance Za matching that of target tissues
  • The possibility for population inversion

Question 6

Question
Light is monochromatic when:
Answer
  • It is a single wavelength λ
  • It propagates in the same direction
  • It propagates in-phase

Question 7

Question
The output mirror of laser resonator is:
Answer
  • Semi-transparent
  • Completely transparent
  • Non-transparent (opaque)

Question 8

Question
The laser can be:
Answer
  • A flux of protons
  • A flux of electrons with the same energy
  • An electromagnetic radiation with specific properties

Question 9

Question
The laser is:
Answer
  • Radionuclide generator for generating metastable radionuclide 99m Tc
  • Generator of light with specific properties
  • Ultrasound generator

Question 10

Question
Light generation in a laser is a result of:
Answer
  • Spontaneous electron transitions
  • Stimulated electron transitions
  • Spontaneous and stimulated transitions of electrons

Question 11

Question
Separation of tissue fragments with a laser, without causing necrosis to underlying cells is called:
Answer
  • Denaturation of proteins
  • Coagulation
  • Photoablation

Question 12

Question
Electromagnetic waves are coherent when:
Answer
  • They oscillate with the same frequency, and with constant phase difference.
  • They have the same wavelength λ
  • They propagate in the same plane.

Question 13

Question
What is the definition for population inversion?
Answer
  • More electrons occupy high energy levels than lower energy levels
  • Fewer electrons occupy high energy levels than lower energy levels
  • There are vacant electron energy levels.

Question 14

Question
Laser radiation DOES NOT have the properties of:
Answer
  • Coherence and polarization
  • Emission in the visible spectrum only
  • Collimation (Directionality)

Question 15

Question
What properties summarize laser light the best:
Answer
  • Monochromatic, Coherent, Collimated
  • Polychromatic, Polarized, Collimated
  • Monochromatic, Coherent, Diffracted

Question 16

Question
Lasers produce light with specific properties through:
Answer
  • Spontaneous emission
  • Stimulated emission
  • Fluorescence

Question 17

Question
Laser endoscopes are preferred to light endoscopes. Which of the statements below is NOT a factor for this choice:
Answer
  • They can eliminate infrared light from the emission spectrum (through a suitable choice of gain medium)
  • They provide optimal illumination of examined organs
  • Examination is more comfortable for the patient

Question 18

Question
PDT of endobronchial cancer uses a laser of 630 nm wavelength. In what of the range is this emission:
Answer
  • UV Range
  • IR Range
  • Visible Range

Question 19

Question
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:
Answer
  • λ = 390 nm
  • λ = 500 nm
  • λ = 630 nm

Question 20

Question
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:
Answer
  • Red
  • Orange
  • Blue

Question 21

Question
In photo-dynamic therapy, malignant tissue is selectively destroyed by a combination of:
Answer
  • Photosensitizing drug (photosensitizer) and the presence of oxygen
  • Photosensitizer, sunlight and oxygen
  • Photosensitizer and laser light

Question 22

Question
Photodynamic therapy based on:
Answer
  • Existent singlet oxygen (1 O2) in cancer tissues
  • Singlet oxygen (1 O2) generation upon irradiation
  • Molecular oxygen (O2) generation upon irradiation

Question 23

Question
In a optical microscope the object is located at a distance
Answer
  • Less than the focal length of the objective lens
  • More than the focal length but less than double the focal length of objective
  • Exactly at the focal length of the objective lens

Question 24

Question
In an optical microscope, where is the object located with respect to the eyepiece lens:
Answer
  • Less than the focal distance of the eyepiece
  • Further than the focal distance, but less than double the focal distance of the eyepiece
  • At the focal distance of the eyepiece lens

Question 25

Question
The image formed by the microscope lens is:
Answer
  • Real
  • Virtual
  • Real and Reduced

Question 26

Question
The image formed by the microscope eyepiece is:
Answer
  • Real
  • Virtual
  • Real and Reduced

Question 27

Question
The image formed by a compound microscope is:
Answer
  • Real, Magnified and Reversed
  • Real, Magnified and Erect (upright)
  • Virtual, Magnified and Reversed

Question 28

Question
What feature of the human eye limits the maximum magnification of optical microscope:
Answer
  • The Optic Power
  • The Resolution
  • The Spectral Sensitivity

Question 29

Question
A negative magnification always means that the image is:
Answer
  • Erect
  • Real
  • Virtual
  • Inverted

Question 30

Question
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:
Answer
  • The image cannot be directly observed with the eyes
  • UV rays are dangerous
  • No powerful sources of UV light exist
  • UV rays change the objects under examination.

Question 31

Question
After passing through a convex lens, rays of light traveling parallel to the axis, will be refracted to the lens:
Answer
  • Center
  • Principle focus
  • Remain parallel

Question 32

Question
When an object is located at distance greater than two focal lengths in front of a converging lens, the image will be:
Answer
  • Real and Enlarged
  • Virtual and Enlarged
  • Real and Reduced
  • Virtual

Question 33

Question
Virtual images formed by converging lenses would appear:
Answer
  • Bigger
  • The Same Size
  • Smaller

Question 34

Question
What wave phenomenon allows the existence of optical microscopes:
Answer
  • Diffraction
  • Refraction
  • Interference

Question 35

Question
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:
Answer
  • Get better
  • Get worse
  • Stay the same

Question 36

Question
Electron microscopes have better resolution than light microscopes. This is because:
Answer
  • Electrons are faster than light
  • Electrons have more energy than light
  • Electrons have shorter wavelengths than light

Question 37

Question
Electron microscopes use special lenses such as:
Answer
  • Optical Lenses with high index of refraction
  • Optical Lenses with low index of refraction
  • Magnetic lenses

Question 38

Question
The human eye is most sensitive to:
Answer
  • Blue light
  • Green light
  • Red light

Question 39

Question
Which wavelength λ is not perceived by the human eye:
Answer
  • 500 nm
  • 1000 nm
  • 620 nm

Question 40

Question
The optical power of the human eye is approximately equal to:
Answer
  • 0.5 dpt
  • 7 dpt
  • 17 dpt
  • 70 dpt

Question 41

Question
2/3 of human eyes optical power is due to the air-cornea interface. This is because:
Answer
  • Refractive indices of air and cornea have greater difference, compared to other refractive surfaces in the eye.
  • The cornea has the largest curvature
  • The cornea is thicker than the lens

Question 42

Question
The image formed on the retina of the human eye is at a distance:
Answer
  • Greater than the double focal length of the eye's lens
  • Equal to the double focal length of the eye's lens
  • Less than the double focal length of the eye's lens

Question 43

Question
The image formed on the retina is:
Answer
  • Real, Enlarged and Inverted
  • Real, Reduced and Inverted
  • Real, Reduced and Erect

Question 44

Question
Nature has deprived human eyes from IR vision, which some animals poses. Is this expedient:
Answer
  • No. Human optical receptors are less adept.
  • No. Humans cannot hunt at night.
  • Yes, The eye is a powerful source of IR and will be blinded by self emission.

Question 45

Question
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?
Answer
  • Myopic eyes look semi-closed and hyperopic eyes look wide open
  • Myopic lenses have thicker periphery, hyperopic have thicker center part
  • Pupils of myopic eyes look small and pupils of hyperopic eyes look enlarged.

Question 46

Question
Which human organ is "responsible" for inter-eye coordination:
Answer
  • The thyroid gland
  • The vestibular apparatus
  • The brain

Question 47

Question
Astigmatism is due to:
Answer
  • Non-uniform curvature of eye lens:
  • Lack of coincidence of eye's anatomical and optical exes
  • Non-uniform curvature of the cornea

Question 48

Question
The stroboscopic effect is due to:
Answer
  • The ability of the optical receptor to retain images for certain time
  • The ability of the optical receptor to determine the distances by eye (the so called estimation by sight)
  • The volumetric (three-dimensional) vision.

Question 49

Question
What type of lenses are used for correction of myopia (short-sightedness)
Answer
  • Cylindrical
  • Spherical, Diverging
  • Spherical, Converging

Question 50

Question
What type of lenses are used for correction of hypermetropia (far-sightness)
Answer
  • Spherical, Diverging
  • Spherical, Converging
  • Cylindrical

Question 51

Question
What type of lenses are used for correction of astigmatism:
Answer
  • Sphero-cylindrical
  • Cylindrical
  • Spherical, Diverging

Question 52

Question
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:
Answer
  • Fish eyes are rounder than human eyes
  • The water surface is curved
  • Sound travels faster in water than in air
  • Light travels faster in air then in water

Question 53

Question
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:
Answer
  • The higher pressure underwater
  • The speed of light in water
  • The need to collect light from wider angles

Question 54

Question
The following can be described as refractive disorders of the eye:
Answer
  • Myopia, Hyperopia, Strabismus
  • Myopia, Hyperopia, Astigmatism
  • Myopia, Presbyopia, Colour blindness
  • Answers A + B

Question 55

Question
Underwater vision (for humans) is blurry. The focusing power of the cornea is greatly reduced when in contact with water. Why is that? :
Answer
  • Because of additional pressure from water molecules
  • Index of refraction of water is greater than index of refraction of air.
  • Index of refraction of water is similar to the index of refraction of the cornea.

Question 56

Question
Which statement describes correctly the photoreceptor cells of the retina
Answer
  • Cones have better sensitivity but lower resolution than rods
  • Rods have better sensitivity but a lower count then cones
  • Cones have higher resolution but lower sensitivity than rods.

Question 57

Question
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?
Answer
  • Blue and green
  • Red and blue
  • Green and Red

Question 58

Question
Human eyes are the most sensitive to green light at 550 nm wavelength. What is the best explanation for this adaption:
Answer
  • Green light is between the red and the blue
  • Green light is usually brighter than red
  • Green light from the sun arrives in greater intensity.

Question 59

Question
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?
Answer
  • Ultrasound
  • Ultraviolet
  • Infrasound
  • Infrared
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