Physics exam
MCQ Contrast media consist of elements with 1) higher atomic number 2) lower atomic number 3) inert gases 4) metalloids
higher atomic number
MCQ The energy passing through unit area is
intensity of x-ray
adhsesion
intermolecular force between different type of molecules
cohesion
intermolecular force between same type of molecules
MCQ Bone thickness is equal to [c - the speed of the sound wave (in m/s); t - time of travelling in s)
(c*deltat)/2
MCQ As an ultrasound pulse moves through tissue in a patient's body it will undergo a change in:
-Intensity (laut powerpoint vom letzten jahr als einziges sicher) Amplitude (Energy), Physical size and Discussion: The frequency of the ultrasound pulse is determined by the transducer and does not change as the pulse moves through the patient's body. However, the pulse is being continuously absorbed (attenuated) which results in a reduction of pulse amplitude and intensity. The physical size of the pulse (in the lateral direction) changes depending on the focusing characteristics of the transducer. Reference: Physical Principles of Medical Imaging, 2nd Edition. pp. 374, 381, 385
MCQ With the gel between skin and transducer the percentage of reflected intensity of ultrasonic is 1) 0.0005 2) 0.0003 3) 0.0008 4) 0.0006
0.03%/0.003
MCQ A sound source sends waves of 400 Hz. It produces waves of wavelength 2.5 m. The velocity of sound waves is
1000 m/s (frequency x wavelenght = speed)
MCQ The wavelength of x-rays is in range
10^-8 till 10^-13
MCQ In x-ray production, the kinetic energy of an electron arriving at anode is
200 keV
MCQ An alpha particle is accelerated through a potential difference of 10 kV. Its gain in kinetic energy is
20keV, because it has protons
MCQ A radio-isotope has an activity of 400 Bq and a half-life of 8 days. After 32 days the activity of the sample is
25Bq (aber auch eher unsicher)
MCQ A particle of charge -0.04 C is projected with speed 2 × 104 m/s into a uniform magnetic field, B, of strength 0.5 T. If the particle's velocity as it enters the field is perpendicular to B, what is the magnitude of the magnetic force on this particle?
400N Since v is perpendicular to B, the strength of the magnetic force, FB, is just qvB, where q is the magnitude of the charge. In this case, then, we find that FB = (0.04 C)(2 × 104 m/s)(0.5 T) = 400 N
MCQ The diagram shows four possible electron energy levels in the hydrogen atom. The number of different frequencies in the emission spectrum of atomic hydrogen that arise from electron transitions between these levels is
6
MCQ A sample contains an amount of radioactive material with a half-life of 3.5 days. After 2 weeks the fraction of the radioactive material remaining is
6.25%
MCQ The angular frequency of precision of protons in an external magnetic field (MRI method) is called
is called Larmor frequency
MCQ A freshly prepared sample contains 4.0 μg of iodine-131. After 24 days, 0.5 μg of iodine-131 remain. The best estimate of the half-life of iodine-131 is
8 days
unit of consumed energy
joule
another unit for consumed energy is
kWh
MCQ The first condition necessary to achieve equilibrium is the net external force on the system must be zero. Which of given case in figure is in equilibrium. (a)
A
MCQ The Achilles tendon is attached to the back of the foot as shown in the image. If a man rises to the one point of the tarsal, then what kind of lever is it?
lever of strength
MCQ Refractive index of a material is
light refractive index in dependence on wavelength
MCQ In the colorimetry, dye concentration dependence of the absorption band peak is:
linear
MCQ The diagram shows some of the energy levels of a hypothetical atom. The atom is excited to the energy level n = 4. Which of the following transitions will produce a photon of the longest and the shortest wavelength?
longest wavelength/shortest frequency 4-->3 shortest wavelength/ longest frequency 4-->1
MCQ Soft x-rays have
lower energy than hard x-rays
MCQ Specific heat capacity measures:
measures the amount of energy required to increase the temperature of a substance the specific heat (also called specific heat capacity) is the amount of heat required to change a unit mass (or unit quantity, such as mole) of a substance by one degree in temperature.
MCQ When heat is absorbed:
molecules move more rapidly
MCQ Two monochromatic, coherent light waves after interference deletes each other when the phase shift between the waves is equal to:
multiple of the half wave of light (nichts zu gefunden)
MCQ A radioactive isotope has an initial activity A0 and a half-life of 1 day. The graph shows how the activity A varies with time. The ratio is equal to which of the following?
A1/A3
MCQ In the case of traditional photoluminescence we can expect shift between maximums of excitation and emission spectra called Stoke's shift. Which of these graphs represents Stoke's shift?
Absorption links, emission rechts Maximum for emmited light spectrum will be smaller for absorbed light spectrum
MCQ The volume of the sound is characterized by?
Amplitude
MCQ Kirchhoff's law of thermal radiation states that
At thermal equilibrium, the emissitivity of a body surface equals its absorptivity
MCQ Point A is at lower electrical potential than point B. An electron between them on the line joining them will
B (A has lower potential (we can denote it by -) B has high potential (+) Electron (-)will move towards B (+) As electrons flow from low to high potential region (or in easy terms the opposite + attracts - )
MCQ Urine absorption spectrum more likely to be:
Band spectrum with a strong absorption band at about 450 nm
MCQ SI unit for Radioactivity is:
Bequerel (Bq)
The ECG does not measure
Blood flow of heart
MCQ The Geiger-Marsden (Rutherford) experiment provides evidence for
Dense positively charged nucleus
MCQ The spectrum observed when white light is shone through a prism is best explained by:
Dispersion
MCQ The repetition of a sound produced by the "reflection of sound waves" from an obstructing surface, loud enough and received late enough to be perceived as distinct from the source?
Echo
Upper image in the figure 5.1. represents emission spectrum Lower image in the figure 5.1 represents absorption spectrum
Emission lines are coloured, absorption lines are black
MCQ Stefan-Boltzmann law states that
Energy of thermal radiation is proportional to temperature of radiating object in power of 4
MCQ The process by which a heavy nucleus splits into two lighter nuclei is known as
Fission
MCQ Which of the following graphs best shows the variation with nucleon number N of the binding energy per nucleon E?
Füg mal bitte das Bild aus dem Word dokument ein D
MCQ The thickness of material which decreases the intensity of x-ray material to half of original value is
Half-value layer, thickness needs to be doubled
Which kind of replacement of a capillary will change the meniscus of the water.
If a thin capillary tube be replaced with another tube with smaller diameter, then water will change its meniscus.
Capillarity is explained by cohesion and adhesion
If adhesion is greater than cohesion then capillary action can happen.
In which case liquid tries to minimize the contact area with the surface?
If the adhesion is smaller than cohesion
MCQ According to Wien's displacement law, which of these spectral lines corresponds to black body at highest temperature?
Immer die oberste
MCQ Wien's displacement law states that
In case of black body, radiation mininum will switch to shorter wavelengths when body temperature increseases
MCQ The diagram below shows a circuit involving a photoelectric cell. When UV light is shone onto the metal cathode, electrons are emitted establishing a photocurrent. Which of the following changes could cause the photocurrent to stop?
Increasing the potential difference of the power supply
MCQ Two charges are separated by a distance d. If the distance between them is doubled, how does the electric potential between them change?
Quartered Careful observations show that the electrostatic force between two point charges varies inversely with the square of the distance of separation between the two charges. That is, the factor by which the electrostatic force is changed is the inverse of the square of the factor by which the separation distance is changed. So if the separation distance is doubled (increased by a factor of 2), then the electrostatic force is decreased by a factor of four (2 raised to the second power)
MCQ Frequencies below 20Hz are called?
Infrasound
MCQ What is an octave?
Interval between one musical pitch and another with half or double its frequency
MCQ In the Rayleigh scattering, scattered light intensity is:
Inversely proportional to wavelength to the fourth power
MCQ The radii of nuclei can be estimated from experiments involving
Involving the scattering of charged particles
MCQ What is a process during which the temperature remains constant?
Isothermal process
MCQ What is the thermodynamic temperature scale in the SI system?
Kelvin
What is kinematic viscosity?
Kinematic viscosity is the ratio between dynamic viscosity and density of the liquid
MCQ The light dispersion is:
Light refractive index dependence on the wavelength
MCQ In turbidimetry
Light scattering is measured
Small liquid drops assume spherical shape because
Liquid tends to have the minimum surface area due to surface tension
In ideal liquid there would be...
No viscosity
MCQ The energies of alpha particles and of gamma-rays emitted in radioactive decay are discrete. This observation is evidence for
Nuclear energy levels
MCQ A person is lying down in bed. In the aorta has developed an extension or aneurysm. The aortic radius Rao is 1 cm. Aneurysms radius Ran is 4 cm. Which of the answers is correct?
P(ao) larger and v(an) higher
MCQ A person is lying down in bed. Arterial stenosis is developed in artery. Radiuss of normal artery Rart is 1cm and radiuss of stenosis Rsten is 0,4cm. Blood flow velocity is in artery is vart and in stenosis vsten. Part and Psten is accordingly pressure in artery and stenosis. In the conditions of stenosis, which of the answers is correct?
P(sten) larger and v(art) higher,
MCQ Unit of loudness level for pure tone?
Phon
How can you define power?
Power is defined as energy per time.
What happens when the speed of the flow increases?
Pressure decreases
MCQ According to Pauli exclusion principle which quantum numbers should be different for two electrons in the same orbital?
Principle spin qunatum numbers
MCQ The graph below shows the number of nuclei N of a radioactive isotope as a function of time t. The slope of the curve at any given time is
Proportional to the number of radioactive nuclei remaining at that time. (nicht nachgeguckt)
MCQ A nucleus of the isotope potassium-40 decays to a nucleus of the isotope argon-40. The reaction equation for this decay may be written as (picture) Which of the following correctly identifies the proton number of argon-40 and the particle X?
Proton number Z is 18 (loses one) and beta positive (e+)
MCQ A driving force in tune with the natural frequency?
Resonannce
MCQ In quantum mechanics, what is the equation that describes how the quantum state of a physical system changes with time?
Schroedingers equation
MCQ SI unit for equivalent Dose is:
Sievert (Si)
MCQ What kind of physical characteristic of a particle gives rise to a gyromagnetic ratio?
Spin/(Magnetic moment)
MCQ In the Geiger-Marsden experiment α-particles are scattered by gold nuclei. The experimental results provide evidence that
That most of the mass and positive charge of an atom is concentrated in a small volume
MCQ The frequency range of sound a human ear can detect?
The human range is commonly given as 20 to 20,000 Hz
MCQ Heisenberg's uncertainty principle states that
The more precisely the position of some particles is determined, the less precisely its momentum can be known and vice versa
Poiseuille`s Law explains the effect of the three factors on peripheral resistance.
The smaller the radius of the vessel, the higher the resistance to blood flow
MCQ Which from followings are not gas lasers:
Thulium
What are sound waves in the range above 20,000 hertz?
Ultrasound
What is the resistance that fluid offers to flow when subject to a shear stress called?
Viscocity is resistance that a fluid offers to flow when subject to a shear stress.
What happens to viscosity when attraction between particles is increased?
Viscosity increases
MCQ The unit of the intensity level of the sound?
Watt per squaremeter (decibel)
What happens to viscosity when temperature is increased?
When temperature is increased, viscosity decreases.
MCQ With the increase of body temperature, the radiation wavelength decreases. This law is called:
Wien's displacement law
MCQ If fast moving electrons rapidly decelerate, then rays produced are
X-rays
MCQ The nuclear equation below is an example of the transmutation of mercury into gold. + X The particle X is a _____
Z=18 und beta+
MCQ The type of x-rays used to detect the break in bone is
hard x-rays
MCQ Heat is
heat is transfer of energy from the system with higher temperature to the system with lower temperature
MCQ Conduction is a
heat transfer
MCQ Electromagnetic waves are produced by
accelerating charges
MCQ Which of the following correctly describes the nature of the energy spectra of alpha, beta, and gamma radiation?
alpha discrete beta continuous gamma discrete
MCQ The gradual decrease in the ultrasound intensity as it passes through the tissue is called
attenuation
MCQ The gradual decrease in the x-ray beam intensity as it passes through the material is called
attenuation
MCQ Photons always propagate with speed c, but light appears to travel at a speed different from c in dense media. How can we account for this phenomenon?
because a medium is a different reference frame to vacuum, so the difference in the observed speed of light is a consequence of relativity
MCQ Different nuclides spontaneously undergo radioactive decay, emitting either α, β or γ radiation. Which of the following correctly identifies all the emissions that do not have discrete energies?
beta
MCQ Which of the following correctly identifies the three particles emitted in the decay of the nucleus 45/20Ca into a nucleus of 45/21Sc?
beta negative, neutrino (eventuell gamma)
MCQ One reason why the sky appears blue is because:
blue light is scattered to a greater extent than red light
MCQ The radii of nuclei may be determined by
by scattering charged particles
Ability of body to store electrical charge
capacity
MCQ A system which consists of fixed amount of mass and no mass can cross its boundary called
closed system
MCQ Bones look white in x-ray photograph because
comparing to soft tissues, bones are good absorbers of xrays
MCQ The shape of sound reflective surface which increases diffusion by scattering the sound is
convex
Good conductors
copper
To increase optical instrument resolution it is needed to
decrease wavelength of light and increase numerical aperture.
MCQ Acoustic impedance depends on:
density of the tissue and speed of the sound wave (density*speed of sound wave)
MCQ Light of wavelength is incident on a metal surface in a vacuum. Photoelectrons are emitted from the surface of the metal. Which of the following best shows the variation with of the maximum kinetic energy EK of the emitted electrons?
die die ein bisschen rechts anfängt und linear steigt
MCQ Piezoelectricity means
electricity resulting from pressure
MCQ Which of the following is a correct statement associated with the photoelectric effect?
eletron emission is instantaneous in photoelectric effect
MCQ The attenuation coefficient depends on the
energy of x-ray photons
MCQ The binding energy of a nucleus is defined to be the
energy released when a nucleus is formed from its individual constituents
MCQ Intensity of light, passing through the substance, decrease:
exponentially
Soft x-rays have longer wavelenght than UVA radiation
false
soft x-rays have lower frequency than micorwaves
false
electric current
flow of electric charge
electromagnetic wave attenuation coefficient
fraction of a beam of a beam of x-rays or gamma rays that is absorbed or scatteredper unit thickness of the absobrer
MCQ If the increasing light wavelength refractive index decreases, then it is:
normal dispersion (For visible light, refraction indices n of most transparent materials (e.g., air, glasses) decrease with increasing wavelength λ)
Sound and light waves both
obey the laws of reflection
MCQ The speed of ultrasound depends upon
on the material
MCQ A photon has a chance of being absorbed by an atom, only if:
only if it has the same frequency as the natural frequency at which electrons in the atom like to vibrate and this can be explained using quantum mechanics
MCQ A good x-ray source should produce x-rays of narrow beam and
parallel x-rays
MCQ De Broglie hypothesis states that
particles can act like waves
Comparing two ultrasounds pulses
pulse with higher frequency is penetrating shallower in the tissue the pulse with lower frequence has longer wavelength and vice versa higher frequency has better resolution (shorter wavelength)
MCQ The main idea for the eye pupil is
responsible for controlling amount of light entering the eye
MCQ The "persistence" of sound in a particular space after the source of sound has stopped is called
reverberation
MCQ The persistence of sound after the source of sound has stopped?
reverberation
Which one of the following materials is the best insulator?
rubber
Solenoid is
several wire coil loops stacked together
MCQ The hardness of x-ray beam can be increased by increasing
the voltage
MCQ When objects are at different temperatures heat is transferred from
the warmer object to the cooler object
MCQ A sound wave which has frequency higher than the upper limit of human hearing is
ultrasound
MCQ Larmor frequency depends upon the
upon the individual atom´s nucleus.
Isometric/isochoric process is thermodynamic process where
volume is held constant.
MCQ By using the piezo-electric substances
we can create ultrasound
MCQ to make sure that Scattered x-ray beams approach the detector screen the anode inside has to be aligned in an angle
wrong
