Medical Biophysics Final Exam || All Questions Answered Correctly.
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Course
Medical Biophysics
Institution
Medical Biophysics
radiation source correct answers - isotropic radiator: negligible size, radiates equally in each direction; shoots out in whole solid angle of 4pi radians
- anisotropic: it radiates with different strength in various directions
radiation correct answers the propagation of energy; it starts from...
Medical Biophysics Final Exam || All Questions Answered
Correctly.
radiation source correct answers - isotropic radiator: negligible size, radiates equally in each
direction; shoots out in whole solid angle of 4pi radians
- anisotropic: it radiates with different strength in various directions
radiation correct answers the propagation of energy; it starts from a source, and after
propagation, reaches its target
irradiated target correct answers the target to which the radiation is targeted
reasons for a decrease in radiation "strength" correct answers - type of the traversed medium
- depth of the traversed medium
- intensity of the incident radiation
- depicted by attenuation law
radiant power (P) correct answers - strength of the source of radiated power
- emitted energy per unit time
- higher the number of emitted current line, the higher the strength
- does not include information on direction
radiant emittance correct answers - radiant flux emitted per unit area
irradiance (M, Ein) correct answers - power incident on a surface of unit area
- radiation may arrive from all directions
radiant flux (Ie) correct answers - amount of energy that can be carried during time, t (watts)
- characterizes the radiation
radiant flux density/intensity (Je) correct answers - the amount of radiant flux (or power)
crossing a unit of area
- measured in W m-2
- also known as intensity or irradiance
solid angle (omega) correct answers - radian is the unit
- defined as the ration of the surface of a conical section of a sphere and the squared radius
(check formula)
geometrical optics correct answers using the model of light rays to say that light goes in straight
propagation
normal of incidence (optical axis) correct answers perpendicular to the glass plane
,fermat's principle correct answers light travels in the path that takes the least time (not
necessarily the path with least distance)
propagation of light in a straight line correct answers - light travels in straight lines in a
homogenous substance
- when in comes in contact with another medium, it can either get reflected or refracted
reflection correct answers - angle of incidence the angle of reflection are the same (alpha and
alpha prime)
- incident and reflected are on the same plane
- angle of selection equals the angle of incidence
refraction correct answers - light moves from one medium to another medium, and the path of
light changes
- angle of incidence different than the angle of refraction (alpha and beta)
- snell's law
- in one plane
total internal reflection correct answers - occurs when light strikes medium at an angle that is
larger than the critical angle
- optically denser medium to optically less dense
- selection inside of the medium
- reason why we see snell's window
angles (alpha, beta) correct answers - alpha: angle between incident ray and optical axis
- beta: angle between refracted ray and the optical axis
absolute and relative indices of refraction correct answers - absolute: is that of a certain material
- relative: compares the refractive indices of two mediums
law of propagation correct answers when we follow geometric optics, where the light propagates
in a straight line, we would expect the light spreads in a straight propagation
light ray correct answers can be considered as extremely thin parallel light beams
optical lens correct answers a transmissive optical device that focuses or disperses a light beam
by means of refraction
- simple lens consists of a single piece of transparent material
- compound lens consists of several simple lenses (elements), usually arranged along a common
axis
optical path length correct answers - the product of the geometric length of the path light follows
through the system, and the index of refraction of the medium through which it
propagates(OP=GL*R.I.)
- a difference in optical path length between two paths is often called the optical path difference
(OPD)
,- important because it determines the phase of the light and governs interference and diffraction
of light as it propagates
object distance (o) correct answers distance from the object to the principle plan of lens
image distance (i) correct answers distance from the principle plane of the lens to the image
formed
focal length (f) correct answers - the distance between the center of a convex lens or a concave
mirror and the focal point of the lens or mirror — the point where parallel rays of light meet, or
converge
magnification (M) correct answers ratio of the image and object size that can also be calculated
using distance
snell's law correct answers or inverted
geometric resolution correct answers - our fovea centralis is hexagonal like a honey comb
- when landolt's ring is placed into these honey combs, whatever hexagon that it covers is the
area that we see as image
- if there is not even a single hexagon available for a single break, then we cannot resolve the
ring and the break will merge with the ring ??????
simple magnifier correct answers when the object is closer than the focal point, the virtual image
forms behind the object, enlarged, with the image distance of -I (check formulas, image)
depth of field correct answers - distance between the near point of vision and the far point of
vision that is giving a focused image
- really depends on the condition of the eye
- in normal sight, anything beyond 25 cm is in depth of sight, while in myopia it is very close
(hyperopia very far)
light interference correct answers - every time peaks are on top of each other, the waves are in
phase (constructive interference)
- destructive interference between where peaks of the wave do not overlap (dark region)
- difference in path length is the wavelength
diffraction correct answers - what happened in the huygen-fresnel experiment
- spreading of light after interacting with the small slit
polarization correct answers - as light propagates as a transverse wave, it oscillates oriented to a
preferred orientation (property of waves that can oscillate with more than one orientation)
- refers to the polarization of the electric field
- light travels in 3D, and generally unpolarized with equal probability of all the planes of
oscillation
, - by using a polarizing filter, we can separate the light rays to be oscillating in the direction we
want
- light in the form of a plane wave in space is said to be LINEARLY polarized
other forms of polarization depend on the amplitude and phase correct answers - if light is
composed of two plane waves of equal amplitude but differing in phase by 90 degrees, then the
light is said to be CIRCULARLY polarized
- if two plane waves of differing amplitude are related in phase by 90 degrees, or if the relative
phase is other than 90 degrees, then the light is said to be ELLIPTICALLY polarized
unpolarized light correct answers random compound of elliptically and circularly polarized light
birefringence correct answers - the optical property of a material having a refractive index that
depends on the polarization and propagation direction of light
- these optically anisotropic materials are said to be birefringent (or birefractive)
- the birefringence is often quantified as the maximum difference between refractive indices
exhibited by the material
- crystals with non-cubic crystal structures are often birefringent, as are plastics under
mechanical stress
- birefringence is responsible for the phenomenon of double refraction whereby a ray of light,
when incident upon a birefringent material, is split by polarization into two rays taking slightly
different paths
amplitude (A) correct answers the distance from the centre line (or the still position) to the top of
a crest or to the bottom of a trough
frequency (f) correct answers the number of waves in a given unit of time, Hz
period time (T) correct answers the interval of time between successive occurrences of the same
state in an oscillatory or cyclic phenomenon
wavelength (lambda) correct answers the distance between successive crests of waves
light velocity (c) correct answers speed of light (3x10^8 m/s)
phase correct answers is the position of a point in time (an instant) on a waveform cycle
- a complete cycle is defined as the interval required for the waveform to return to its arbitrary
initial value
phase difference correct answers - the difference, expressed in degrees or radians, between two
waves having the same frequency and referenced to the same point in time
- two oscillators that have the same frequency and no phase difference are said to be in phase
- two oscillators that have the same frequency and different phases have a phase difference, and
the oscillators are said to be out of phase with each other
oscillation correct answers the regular variation of position or magnitude around a central point
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