1913063
Descripción
Pregunta 1
Pregunta
Which substances have both intrinsic, and extrinsic electric conductivity:
Respuesta
-
Conductors
-
Dielectrics (insulators)
-
Semiconductors
Pregunta 2
Pregunta
Dielectrics can be described as having:
Respuesta
-
Free electron states in the valence band
-
Wide (forbidden) band gap, and completely occupied valence band
-
Extrinsic atoms from elements with different valance
Pregunta 3
Pregunta
P-doping of semiconducting germanium (Ge), will create additional energy levels;
Respuesta
-
Near the conduction band of Ge
-
At the forbidden band-gap of Ge
-
Near the valence band of Ge
Pregunta 4
Pregunta
The band-gap width of a dielectric (insulator) is:
Respuesta
-
Narrower than 1 eV
-
Wider than 3 eV
-
Narrower than 0.01 eV
Pregunta 5
Pregunta
Band theory of solids defines conductors as having:
Respuesta
-
An unoccupied (free) electrons states in the valence band
-
A narrow band-gap, and absence of free states in the valence band
-
impurities from elements with lower valence
Pregunta 6
Pregunta
N-doping of semiconducting germanium (Ge), will create additional energy levels:
Respuesta
-
Near the valence band of Ge
-
At the forbidden bang-gap of Ge
-
Near the conduction band of Ge
Pregunta 7
Pregunta
Valence and conductivity bans overlap partially in:
Respuesta
-
Metals
-
Dielectrics
-
Semiconductors
Pregunta 8
Pregunta
Charge carriers of certain type (n or p) will dominate in a semiconductor when:
Respuesta
-
The number of unoccupied electron states in valence and conduction bands are equal
-
The band-gap is large, and the valence band is completely occupied
-
Impurities with lower or higher valence are present
Pregunta 9
Pregunta
What is the difference between dielectrics and semiconductors, according to band theory of solids.
Respuesta
-
The number of electrons in valence band
-
Band-gap is greater or less than 3 eV in width
-
The number of occupied electron in conduction band
Pregunta 10
Pregunta
Current carriers in semiconductors are:
Respuesta
-
Holes only:
-
Electron and Holes
-
Electrons only
Pregunta 11
Pregunta
What type of current carriers are the holes:
Respuesta
-
Positrons
-
Unoccupied electron place-holders (virtual positive charges)
-
Positive Ions
Pregunta 12
Pregunta
How does intrinsic conductivity of semiconductors depend on temperature?
Respuesta
-
It increases with Temperature
-
It decreases with Temperature
-
It does not depends on Temperature
Pregunta 13
Pregunta
How does intrinsic conductivity of semiconductors depend on Temperature?
Respuesta
-
A narrower band-gap results in higher conductivity.
-
A narrower band-gap results in lower conductivity.
-
It does not depend on the width of the band-gap.
Pregunta 14
Pregunta
What are the current carriers in a P-N junction, upon application of forward bias?
Respuesta
-
Electrons and Holes
-
Only Electrons
-
Only Holes
Pregunta 15
Pregunta
Using OHM's LAW: In order to assess the medicinal effect of a substance, in dermatology, the skin impedance Z is studied by:
Respuesta
-
Electromagnetic Waves
-
An Alternating Electric Current
-
A Direct Electric Current
-
A Magnetic Field
Pregunta 16
Pregunta
The electric impedance of biological tissues is composed of:
Respuesta
-
R and Xc
-
XL and Xc
-
R and XL
Pregunta 17
Pregunta
Using OHM's LAW: Capacity reactance of an AC circuit is equal to:
Respuesta
-
wL + 1/wC
-
1/wC
-
wL
Pregunta 18
Pregunta
Using OHM's LAW: The direction of electrical current fluctuates with time in:
Respuesta
-
One-way rectified current
-
Direct Current
-
Alternating Current
Pregunta 19
Pregunta
Using OHM's LAW: Ohm's law states:
Respuesta
-
U = IR
-
R = I/U
-
R = UI
Pregunta 20
Pregunta
Using OHM's LAW: Electric current is:
Respuesta
-
A flow of elementary particles
-
A flow of charged particles
-
An electromagnetic wave
Pregunta 21
Pregunta
The unit for electrical conductivity is:
Respuesta
-
Ohm
-
Electrical conductivity is a dimensionless
-
Siemens [S]
Pregunta 22
Pregunta
The unit for electrical resistance is:
Respuesta
-
Voltage
-
Ampere
-
Ohm
Pregunta 23
Pregunta
What type of tissue or body fluid have the highest electrical conductivity:
Respuesta
-
Cerebrospinal fluid
-
Blood Plasma
-
Blood
-
Skin and Bones
Pregunta 24
Pregunta
What is the frequency of direct currents (DC)
Respuesta
-
50 MHz
-
50 Hz
-
DC has no frequency
Pregunta 25
Pregunta
What type of electrical current is a lightning bolt?
Respuesta
-
Direct current (DC)
-
High Frequency AC
-
Low Frequency AC
Pregunta 26
Pregunta
What type of electrical current is a galvanic current?
Respuesta
-
High Frequency AC
-
Low Frequency AC
-
Low Direct Current
Pregunta 27
Pregunta
What type of electric impedance is present in the human tissue?
Respuesta
-
Inductive and Capacitive
-
Resistive and Capacitive
-
Resistive and Inductive
Pregunta 28
Pregunta
What type of electric impedance is present in the human tissue?
Respuesta
-
Direct Current Only
-
Alternating Current Only
-
Both, AC and DC can propagate
-
Neither, only electromagnetic waves can propagate.
Pregunta 29
Pregunta
Transducer is a device for:
Respuesta
-
Generation of metastable radionuclides
-
Transformation of energy from one form to another
-
Other name of linear scanner
Pregunta 30
Pregunta
What type of transducer is the piezoelectric crystal? (e.g. transducers in echo-graphs)
Respuesta
-
Generator type
-
Both Parametric and Generator Type
-
Parametric Type
Pregunta 31
Pregunta
What type of transducer is the ionization chamber:
Respuesta
-
Parametric type
-
Both Parametric and Generator Type
-
Generator type
Pregunta 32
Pregunta
Which of the objects mentioned below is a transducer:
Respuesta
-
Permanent magnet of MRI
-
Roentgen film
-
Geiger-Muller Counter
-
Mercury Thermometer
Pregunta 33
Pregunta
Which of the objects mentioned below is NOT a transducer:
Respuesta
-
The ionization chamber
-
The Roentgen Film
-
The Geiger-Muller Counter
-
The pressure gauge of the blood pressure measuring device
Pregunta 34
Pregunta
Which of the following functions are performed by a photocell:
Respuesta
-
It converts chemical energy into electrical energy
-
It converts magnetic energy into electrical energy
-
It converts light energy into electrical energy
-
It converts electrical energy into light energy.
Pregunta 35
Pregunta
Thermocouple is an arrangement of two different metals:
Respuesta
-
To convert heat into electric energy
-
To convert heat into chemical energy
-
To convert electrical energy into heat
Pregunta 36
Pregunta
Which of the following is NOT a transducer
Respuesta
-
The battery of cardiac pacemaker
-
The thermistor
-
The photoelectric cell
Pregunta 37
Pregunta
Which is the most relevant electromyography parameter for determination of damaged tissue
Respuesta
-
Rheobase
-
Chronaxie
-
Coefficient of accommodation
Pregunta 38
Pregunta
In an active electro-diagnostics the source of E.M.F (Electromotive Force):
Respuesta
-
The body of the examined patient
-
The electrocardiograph
-
The stimulation apparatus
-
The electroencephalograph
Pregunta 39
Pregunta
In a passive electro-diagnostics the course of Electromotive Force is:
Respuesta
-
The body of the examined patient
-
The Electrocardiograph
-
The Stimulation apparatus
-
The Electroencephalograph
Pregunta 40
Pregunta
ECG is a method of:
Respuesta
-
Examination of muscles
-
Examination of the brain
-
Examination of the heart
Pregunta 41
Pregunta
EEG is a method of:
Respuesta
-
Examination of muscles
-
Examination of the brain
-
Examination of the heart
Pregunta 42
Pregunta
EMG is a method of:
Respuesta
-
Examination of the muscles
-
Examination of the brain
-
Examination of the heart
Pregunta 43
Pregunta
The active electro-diagnostic differs from the passive one in the fact that source of Electromotive Force:
Respuesta
-
The electromyography
-
The examined organ in the patient's body
-
Apparatus used for electro-stimulation
Pregunta 44
Pregunta
The defibrillator is used to:
Respuesta
-
Replace the heart in operations of the heart
-
Restore the rhythmical contraction and relaxation of the different structures of the heart muscle (the myocard)
-
Support the cardiac output
Pregunta 45
Pregunta
The cardio-stimulator (the pacemaker) is:
Respuesta
-
Self-recording device for measurement of the pulse and blood pressure
-
Substitute of the heart in operations of the heart
-
Generator of electric impulses needed for the cardiac output.
Pregunta 46
Pregunta
The cardio-stimulator (the pacemaker) is supplied by:
Respuesta
-
Biogalvanic elements
-
Small battery installed beneath the patients skin
-
The cosmic radiation
Pregunta 47
Pregunta
For electrostimulation on an object to occur, a minimum threshold stimulus is needed. This electrical stimulus depends on:
Respuesta
-
Electrical pulse current
-
Electrical pulse duration
-
Both, current and pulse duration.
Pregunta 48
Pregunta
Faradization is a method for:
Respuesta
-
Electro-gymnastics using low frequency pulsed current
-
Therapy using high frequency electric current
-
Deep electro-stimulation with two interfering currents, with frequencies 2 - 5 kHz
Pregunta 49
Pregunta
Microwave therapy uses:
Respuesta
-
Electric field generated by an electric current with a frequency of 50 hZ
-
Magnetic field generated by a direct electric current
-
High frequency electromagnetic waves
Pregunta 50
Pregunta
The most suitable frequency magnetic field is used in:
Respuesta
-
20 Hz
-
20 kHz
-
20 MHz
Pregunta 51
Pregunta
High Frequency magnetic field is used in:
Respuesta
-
Capacitive Diathermy
-
MRI Tomography
-
Inductive Diathermy
Pregunta 52
Pregunta
Deep heating of tissues (Therapeutic Diathermia) is applied using a high frequency current of the order of:
Respuesta
-
0.3 - 5 Hz
-
0.3 - 5 kHz
-
0.3 - 5 MHz
Pregunta 53
Pregunta
High frequency AC is less harmful to the body than low frequency AC. This is because high frequency AC:
Respuesta
-
Increases exposure time
-
Passes through the skin without irritation
-
Changes ion polarization
Pregunta 54
Pregunta
Microwave diathermy uses frequency of 2.450 GHz. This frequency is:
Respuesta
-
Higher than microwave oven frequency
-
Lower than microwave oven frequency
-
The same as microwave oven frequency
Pregunta 55
Pregunta
What type of accident is most common during microwave diathermy:
Respuesta
-
Electrocution
-
Burning
-
Neuromuscular Stimulation
Pregunta 56
Pregunta
The most prominent effect of DC on the human body is:
Respuesta
-
Constant orientation of ions (polarization), followed by accommodation
-
Continuous change of polarity and lack of accommodation
-
Vibration of ions around equilibrium position, rotation of electrical dipoles
-
Propagation through skin with irritation.
Pregunta 57
Pregunta
Which of the following effects is NOT characteristic for AC
Respuesta
-
Constant orientation of ions (polarization), followed by accommodation
-
Continuous change of polarity and lack of accommodation
-
Vibration of ions around equilibrium position, rotation of electrical dipoles
-
Propagation through the skin without irritation
Pregunta 58
Pregunta
Which of the following effects is characteristic for low frequency (50 Hz) alternative current:
Respuesta
-
Constant orientation ions (polarization), followed by accommodation.
-
Ions vibrate around equilibrium position, electrical dipoles rotate
-
Passes through the skin with irritation and causes deep heating
Pregunta 59
Pregunta
Which of the following effects is characteristic of high frequency (2 MHz) alternative current:
Respuesta
-
Constant orientation ions (polarization), followed by accommodation.
-
Ions vibrate around equilibrium position, electrical dipoles rotate
-
Passes through the skin without irritation and causes deep heating.
Pregunta 60
Pregunta
Which therapeutic method causes deep tissue heating:
Respuesta
-
High frequency therapy using electric current
-
Thermovision
-
Deep roentgen therapy
Pregunta 61
Pregunta
UHF with high frequency electromagnetic waves (= GHz) are used in:
Respuesta
-
Faradizations
-
Diathermia
-
Microwave Therapy
Pregunta 62
Pregunta
Negative, light aeroions have:
Respuesta
-
A favorable effect on humans
-
A negative biological effect on humans
-
A favorable effect if they are attached to dust particles.
Pregunta 63
Pregunta
Positive Aeroions have:
Respuesta
-
A favorable effect on humans
-
A negative biological effect on humans
-
A favorable effect if they are attached to dust particles
Pregunta 64
Pregunta
The franklinization (electric shower) is a method in:
Respuesta
-
Thermal therapy using infared rays
-
Patient preparation for diagnostic imaging
-
Artificial aeroionotherapy
Pregunta 65
Pregunta
In the Franklilization (electric shower) the negative electrode is:
Respuesta
-
Connected to patients chair
-
Above patients head
-
On the stage where the patients has stepped
Pregunta 66
Pregunta
Favorable effect on the organism have:
Respuesta
-
Light positive aeroions
-
Light negative aeroions
-
None of the aeroions
Pregunta 67
Pregunta
The concentration of light, negative aeroions is higher in:
Respuesta
-
In the forest
-
Small village
-
Industrial Town
Pregunta 68
Pregunta
Iontophoresis uses:
Respuesta
-
US
-
Radioactive sources
-
Direct electric current
-
Alternating electric current
Pregunta 69
Pregunta
Iontophoresis is a method for:
Respuesta
-
Electrodiagnostics
-
Electrostimulation
-
Electrotherapy with drugs
Pregunta 70
Pregunta
During Iontophoresis, if active pharmaceutical ion is positive, the active electrode is:
Respuesta
-
The anode (positive)
-
The Cathode (negative)
-
Either anode with work
Pregunta 71
Pregunta
What is the difference between Sonophoresis and Iontophoresis:
Respuesta
-
The former is therapeutic and the latter is diagnostic
-
The external (physical) stimulus, enabling the insertion of drugs into the tissue
-
The location of application.
Pregunta 72
Pregunta
The constant magnetic field applied to the patient in MRI examination is:
Respuesta
-
Weaker than the earths magnetic
-
Much stronger than the earths magnetic field
-
Equal to the Earths magnetic field.
Pregunta 73
Pregunta
What part of the hydrogen nuclei (protons) are examined tissues participates in the processes of forming a diagnostic image:
Respuesta
-
All protons
-
Minor part (about 0.0001%)
-
All protons from the water molecules.
Pregunta 74
Pregunta
In order to observe the phenomenon of Nuclear Magnetic Resonance (NMR), in an atomic nucleus must be:
Respuesta
-
Metastable
-
Radioactive
-
With a magnetic moment other than zero
Pregunta 75
Pregunta
The contrast between different biological tissues in MRI is obtained from:
Respuesta
-
The decay of electromagnetic waves, passing through them.
-
The difference in density p of tissues
-
The difference in volume concentrations of hydrogen nuclei (proton)
Pregunta 76
Pregunta
Medicinal Substances with anti-oxidation properties are analysed using:
Respuesta
-
Nuclear Magnetic Resonance
-
Electronic Paramagnetic Resonance
-
Radionuclide Methods
-
Colour Doppler
Pregunta 77
Pregunta
The chemical shift is an important parameter for direct observation of the chemical basis of disease, in:
Respuesta
-
SPECT - Single Photo Emission Computer Tomography
-
PET - Positron Emission Tomography
-
CT - Computed Tomography
-
Spectroscopic MRI
Pregunta 78
Pregunta
Which is the most common contrast substance used in MRI
Respuesta
-
99m TC
-
60Co
-
64Gd
-
10B
Pregunta 79
Pregunta
Volume Concentration of Protons is a parameter in diagnostic image formation in:
Respuesta
-
Technography
-
Magnetic Resonance Tomography MRI
-
Positron Emission Tomography - PET
-
Roentgenography
Pregunta 80
Pregunta
Contrast substances used MRI are:
Respuesta
-
Paramagnetic
-
Piezocrystals
-
Photosensitive
Pregunta 81
Pregunta
Contrast substances used in MRI diagnostics modify:
Respuesta
-
The size of the external magnetic field
-
The density of protons p in the examined tissue
-
The times of relaxation T1 and T2 in the examined tissues.
-
The frequency of the high frequency electromagnetic field
Pregunta 82
Pregunta
Longitudinal time of relaxation T1 is a parameter used in:
Respuesta
-
Positron Emission Tomography
-
Echography
-
Magnetic Resonance Tomography
-
Roentgen Computed Tomography
Pregunta 83
Pregunta
Transversal time of relaxation T2 is parameter used in:
Respuesta
-
Positron Emission Tomography
-
Echography
-
MRI
-
Roentgen Computed Tomography (CT)
Pregunta 84
Pregunta
In MRI, the electric signals from different small volume elements (voxels) in examined tissues are distinguished by:
Respuesta
-
The applied gradient magnetic fields
-
Change in the frequency of the high frequency electromagnetic field
-
Introduction (injection) of contrast substance
Pregunta 85
Pregunta
The effect of the high frequency electromagnetic field on examined tissues in MRI is:
Respuesta
-
Dangerous heating
-
Insignificant endogenic heating
-
Electric Excitation
Pregunta 86
Pregunta
For which of the listed below organs and tissues, is MRI the most informative diagnostic imagine method:
Respuesta
-
Soft Tissues
-
Bones
-
Body Cavities
Pregunta 87
Pregunta
MRI coil magnets operate at very low temperature (in liquid helium) so that:
Respuesta
-
The risk of tissue damage is reduced
-
The constant magnetic field is homogenous
-
A superconductivity is achieved - Magnetizing coil wires are very thin.
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