Test Physics Num 1
- 1.
Which of these are dispersions (dispersed systems)? What do we call dispersed systems?
- A.
Salt solutions
- B.
Suspensions, emulsions, aerosols, other mixtures
- C.
Materials which disperse light
- D.
Materials which disperse sound waves
Correct Answer
B. Suspensions, emulsions, aerosols, other mixturesExplanation
Suspensions, emulsions, aerosols, and other mixtures are all examples of dispersed systems. Dispersed systems refer to a type of mixture where one substance is dispersed or spread throughout another substance. In the case of suspensions, solid particles are dispersed in a liquid or gas. Emulsions involve the dispersion of small droplets of one liquid within another immiscible liquid. Aerosols consist of small particles or liquid droplets dispersed in a gas. Other mixtures can also be considered dispersed systems if they involve the dispersion of one substance within another.Rate this question:
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- 2.
Which of the following phenomena is observable when alternating current is applied to live tissues?
- A.
Translational motion of ions
- B.
Dielectric polarization
- C.
Electrostatic induction
- D.
Ion fluctuation
- E.
Electroosmosis
Correct Answer
D. Ion fluctuationExplanation
When alternating current is applied to live tissues, ion fluctuation is observable. This is because the alternating current causes ions within the tissues to move back and forth rapidly. This movement of ions is known as ion fluctuation.Rate this question:
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- 3.
Which of the following phenomena is observable when direct current is applied to live tissues?
- A.
Ion fluctuation
- B.
Dielectric polarization
- C.
Translational motion of ions and the redistribution of their concentrations
- D.
Skin Skin effect
- E.
Electrostatic induction
Correct Answer
C. Translational motion of ions and the redistribution of their concentrationsExplanation
When direct current is applied to live tissues, the ions within the tissues experience translational motion and their concentrations are redistributed. This is because the electric field generated by the direct current causes the ions to move in a specific direction. This phenomenon is observable and can have various effects on the tissues, such as changes in pH levels and cellular functions.Rate this question:
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- 4.
General tissue impedance dispersion?
- A.
The relation of the impedance and the capacitance of the tissue
- B.
The relation of the impedance and the amount of fluid in the tissue
- C.
The relation of the impedance and the strength of the current flowing through the tissue
- D.
The relation of the impedance and the frequency of the current flowing through the tissue
- E.
The relation of the impedance and the frequency of the magnetic field affecting the tissue
Correct Answer
D. The relation of the impedance and the frequency of the current flowing through the tissueExplanation
The correct answer explains that there is a relation between impedance and the frequency of the current flowing through the tissue. Impedance is a measure of the opposition to the flow of alternating current in a circuit. In the context of tissue, impedance refers to the resistance encountered by the current as it passes through the tissue. The frequency of the current affects the impedance because different tissues have different electrical properties that can change with frequency. Therefore, the impedance of the tissue will vary depending on the frequency of the current flowing through it.Rate this question:
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- 5.
Which of the following phenomena is observable when a static magnetic field affects live tissues?
- A.
The rotation of polar particles along the field‘s line of force
- B.
The rotation of paramagnetic particles along the field‘s line of force
- C.
Electrostatic induction
- D.
Thermal phenomena
- E.
Cell polarization
Correct Answer
B. The rotation of paramagnetic particles along the field‘s line of forceExplanation
When a static magnetic field affects live tissues, the phenomenon that is observable is the rotation of paramagnetic particles along the field's line of force. Paramagnetic particles are attracted to magnetic fields and align themselves with the field's direction. This alignment causes them to rotate along the lines of force of the magnetic field. This phenomenon can be observed in certain biological systems where paramagnetic particles are present, such as in some types of cells or tissues.Rate this question:
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- 6.
What is electrophoresis?
- A.
The movement of dispersive particles when affected by gravitational force
- B.
The movement of dispersive particles due to pressure disparity
- C.
The movement of dispersive media when affected by an electric field
- D.
The movement of dispersive particles when affected by an electric field
Correct Answer
D. The movement of dispersive particles when affected by an electric fieldExplanation
Electrophoresis is the movement of dispersive particles when affected by an electric field. This process is commonly used in laboratories to separate and analyze molecules based on their size and charge. When an electric field is applied, charged particles move towards the opposite charged electrode. This movement allows for the separation and identification of different molecules in a sample.Rate this question:
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- 7.
Which of the following phenomena is observable when an alternating electric field affects live tissues?
- A.
A change in cell polarity/polarization
- B.
Electromagnetic induction
- C.
The rotation of paramagnetic particles
Correct Answer
A. A change in cell polarity/polarizationExplanation
When an alternating electric field affects live tissues, it causes a change in cell polarity/polarization. This means that the electric charges within the cells shift and align in response to the alternating electric field. This phenomenon is observable as the cells undergo changes in their electrical properties, which can have various physiological effects on the tissues. It is important to note that electromagnetic induction and the rotation of paramagnetic particles are not directly related to the effect of an alternating electric field on live tissues.Rate this question:
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- 8.
What is observed in tissues due to the Hall effect?
- A.
Cell polarization
- B.
Ion fluctuation
- C.
The production of a voltage difference across the walls of a blood vessel
- D.
Foucault currents? Not the correct one anyway
- E.
Movement of paramagnetic particles
Correct Answer
C. The production of a voltage difference across the walls of a blood vesselExplanation
The Hall effect is the production of a voltage difference across the walls of a blood vessel. This phenomenon occurs when a magnetic field is applied perpendicular to the direction of an electric current flowing through a conductor. In tissues, the Hall effect can be observed as the generation of a voltage difference across the walls of a blood vessel, which can have various physiological implications.Rate this question:
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- 9.
Which of the following phenomena is observable when a static electric field affects live tissues?
- A.
The rotation of paramagnetic particles along the field‘s line of force
- B.
Electrostatic induction
- C.
Electrochemical activation
- D.
Electromagnetic induction
- E.
Thermal phenomena
Correct Answer
B. Electrostatic inductionExplanation
Electrostatic induction is the correct answer because when a static electric field affects live tissues, it can induce a separation of charges within the tissues. This separation of charges can lead to the redistribution of charges and the creation of an electric field within the tissues. This phenomenon is known as electrostatic induction.Rate this question:
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- 10.
Which of the following phenomena is observable when an alternating magnetic field affects live tissues?
- A.
Rotation of polar particles
- B.
Paramagnetic particle fluctuation
- C.
Hall effect
- D.
Ion fluctuation
- E.
Electromagnetic induction
Correct Answer
E. Electromagnetic inductionExplanation
When an alternating magnetic field affects live tissues, electromagnetic induction is observed. Electromagnetic induction is the process by which a changing magnetic field induces an electric current in a conductor. In this case, the alternating magnetic field induces an electric current in the live tissues, causing them to be affected. This phenomenon is commonly observed in various medical procedures and therapies that utilize electromagnetic fields to stimulate tissues and promote healing.Rate this question:
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- 11.
Electrical (ion) mobility is best described as:
- A.
The speed of an ion with a charge equal to an elementary charge (the charge of a single electron or -1.602176634×10−19 C) in an electric field)
- B.
The speed that an ion gains when a 1A electric current is applied
- C.
The speed of an ion in a 1 V/m electric field
- D.
Speed of an ion in a 1 A/m magnetic field
- E.
The force affecting ions in a 1 V/m electric field
Correct Answer
C. The speed of an ion in a 1 V/m electric fieldExplanation
Electrical (ion) mobility refers to the speed at which an ion moves when subjected to a 1 V/m electric field. It is a measure of how easily an ion can move through a medium under the influence of an electric field. The higher the electrical mobility, the faster the ion will move in the electric field. This concept is important in various fields, such as electrochemistry and semiconductor physics, where the movement of ions plays a crucial role.Rate this question:
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- 12.
Nuclear magnetic resonance (NMR) is best described as:
- A.
The magnetisation of material when affected with a constant magnetic field
- B.
The absorbtion of certain frequency electromagnetic waves in material when affected with a constant magnetic field (due to electrons jumping from a lower to a higher energy state in atoms)
- C.
A sudden increase in the amplitude of nuclei fluctation (oscillation) of atoms when affected with a constant magnetic field and certan frequency electromagnetic waves
- D.
The absorbtion of certain frequency electromagnetic waves in material when affected with a constant magnetic field (due to a shift in the magnetic moment orientation of atom nuclei)
Correct Answer
D. The absorbtion of certain frequency electromagnetic waves in material when affected with a constant magnetic field (due to a shift in the magnetic moment orientation of atom nuclei)Explanation
The correct answer is the absorption of certain frequency electromagnetic waves in material when affected with a constant magnetic field (due to a shift in the magnetic moment orientation of atom nuclei). This explanation accurately describes the process of nuclear magnetic resonance (NMR), where the nuclei of atoms align their magnetic moments with an external magnetic field and absorb energy from electromagnetic waves of a specific frequency. This absorption is caused by the shift in the orientation of the magnetic moments of the atom nuclei.Rate this question:
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- 13.
The magnetic moment pm of a current flowing through a conductive ring is equal to: (S – ring area, I – electrical current strength)
- A.
Pm = I/S
- B.
Pm = I*S
- C.
Pm = (I*p)/S
- D.
Pm = (I*S)/p
- E.
Pm = S/I
Correct Answer
B. Pm = I*SExplanation
The magnetic moment (pm) of a current flowing through a conductive ring is equal to the product of the electrical current strength (I) and the ring area (S). This can be represented by the equation pm = I*S.Rate this question:
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- 14.
Which of these correctly expresses the main condition of NMR?
- A.
Hv = gbrβbrB
- B.
Hv = gbrβbrI
- C.
Hv = gbrβbrmbr
- D.
Hv = gbrB
- E.
Hv = gbrβbr/B
Correct Answer
A. Hv = gbrβbrBExplanation
The correct answer is hv = gbrβbrB. This equation correctly expresses the main condition of NMR, which is that the energy of a photon (hv) is equal to the product of the gyromagnetic ratio (g), the magnetic field strength (B), and the nuclear magnetization (β).Rate this question:
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- 15.
Paramagnetic material is best described as a material, with particles that have:
- A.
Electric dipole moment
- B.
Electric quadrupole moment
- C.
Magnetic moment
- D.
Magnetic charge
Correct Answer
C. Magnetic momentExplanation
A paramagnetic material is best described as a material with particles that have a magnetic moment. This means that the particles in the material have a small magnetic field associated with them, which aligns with an external magnetic field. This alignment causes the material to be weakly attracted to the magnetic field. Unlike ferromagnetic materials, paramagnetic materials do not retain their magnetism once the external magnetic field is removed.Rate this question:
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- 16.
The Nyquist Theorem states that:
- A.
A continuous-time signal is only defined at certain moments in time
- B.
A discrete-time signal is described using only the theory of relativity
- C.
The sampling frequency can‘t be lower than 2x the signal frequency
- D.
A continuous-time signal cannot be described
- E.
Discrete-time signals do not appear during biological processes
Correct Answer
C. The sampling frequency can‘t be lower than 2x the signal frequencyExplanation
The correct answer is the sampling frequency can't be lower than 2x the signal frequency. This is known as the Nyquist-Shannon sampling theorem, which states that in order to accurately reconstruct a continuous-time signal from its samples, the sampling frequency must be at least twice the maximum frequency present in the signal. This is to avoid aliasing, where higher frequency components of the signal overlap and distort the reconstructed signal.Rate this question:
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- 17.
Which of these biosignals is of electrical origin?
- A.
Phonocardiogram
- B.
Arterial blood pressure curve
- C.
Seismocardiogram
- D.
Rheocardiogram
Correct Answer
D. RheocardiogramExplanation
The correct answer is rheocardiogram. A rheocardiogram is a biosignal that measures the electrical activity of the heart. It is typically recorded using electrodes placed on the skin, which detect the electrical impulses generated by the heart during each heartbeat. This signal can provide valuable information about the heart's function and can be used to diagnose various cardiac conditions. In contrast, a phonocardiogram measures the sounds produced by the heart, an arterial blood pressure curve measures the pressure of blood in the arteries, and a seismocardiogram measures the vibrations produced by the heart's movements.Rate this question:
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- 18.
Electrocardiogram (ECG) is best described as:
- A.
The evaluation of mechanical heart function
- B.
Electrical heart function
- C.
A measurement of heart function induced change in potential difference between two areas of the body
- D.
The spread of an excitory signal towards the extremities
Correct Answer
C. A measurement of heart function induced change in potential difference between two areas of the bodyExplanation
An electrocardiogram (ECG) is a measurement of heart function induced change in potential difference between two areas of the body. It is a diagnostic test that records the electrical activity of the heart. By placing electrodes on the skin, the ECG machine detects and amplifies the electrical signals produced by the heart. These signals are then displayed as waves on a graph, allowing healthcare professionals to analyze the heart's rhythm and identify any abnormalities. The ECG does not evaluate mechanical heart function or the spread of an excitory signal towards the extremities; it specifically measures the electrical activity of the heart.Rate this question:
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- 19.
The positive and negative charges in a dipole model of the heart are:
- A.
The non-excited and excited heart areas
- B.
The inside and outside of a heart cell
- C.
The positive and negative electrode
- D.
The heart‘s eletrical axis
Correct Answer
A. The non-excited and excited heart areasExplanation
The correct answer is the non-excited and excited heart areas. In a dipole model of the heart, the positive and negative charges represent the non-excited and excited areas of the heart. The non-excited areas have a net positive charge, while the excited areas have a net negative charge. This distribution of charges plays a crucial role in the generation and propagation of electrical signals in the heart, which coordinate its contractions and ensure proper functioning.Rate this question:
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- 20.
The electrical irritability law describes the relation between:
- A.
The maximum irritation current strength and irritation duration
- B.
The lowest possible irritation current strength still able to irritate and irritation duration
- C.
Irritation current strength and voltage
- D.
Lowest and maximum irritation current strength
- E.
Rheobase and chronaxie
Correct Answer
B. The lowest possible irritation current strength still able to irritate and irritation durationExplanation
The electrical irritability law describes the relationship between the lowest possible irritation current strength that is still able to cause irritation and the duration of that irritation. This means that there is a minimum threshold of current strength required to elicit a response, and the longer the current is applied, the longer the irritation will last.Rate this question:
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- 21.
Rheobase is:
- A.
Highest possible irritation current strength
- B.
Lowest irritation current strength when irritation duration is very short
- C.
The lowest current strength still able to irritate
- D.
Longest possible irritation duration
Correct Answer
C. The lowest current strength still able to irritateExplanation
Rheobase refers to the lowest current strength that is still capable of causing irritation. It represents the threshold at which a stimulus becomes noticeable or produces a response. This means that any current strength below the rheobase will not be able to elicit a noticeable irritation, while any current strength equal to or above the rheobase will be able to do so. Therefore, the correct answer is "the lowest current strength still able to irritate."Rate this question:
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- 22.
Chronaxie is:
- A.
The shortest duration of irritation when strength is equal to rheobase
- B.
Highest possible irritation current strength
- C.
Longest duration of irritation
- D.
Shortest duration of irritation when current strength is equal to 2x rheobase
Correct Answer
D. Shortest duration of irritation when current strength is equal to 2x rheobaseExplanation
Chronaxie refers to the shortest duration of irritation required to stimulate a muscle or nerve fiber when the current strength is equal to 2 times the rheobase. In other words, it is the minimum amount of time needed to elicit a response from the muscle or nerve fiber at a specific current strength. This indicates that chronaxie is a measure of the excitability or responsiveness of the muscle or nerve fiber, with a shorter duration indicating a higher level of excitability.Rate this question:
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- 23.
The minimal stimulation energy principle states that:
- A.
Tissue is damaged the least when stimulated with weakest current
- B.
The lowest amount of energy is used when current strength is equal to rheobase
- C.
The lowest amount of energy is used when stimulation duration is equal to chronaxie
- D.
The lowest amount of energy is used when stimulation duration is equal to 2x chronaxie
Correct Answer
C. The lowest amount of energy is used when stimulation duration is equal to chronaxieExplanation
The minimal stimulation energy principle states that the lowest amount of energy is used when the stimulation duration is equal to the chronaxie. Chronaxie is the minimum duration of an electrical stimulus required to produce a response from a tissue at twice the rheobase current strength. By using a stimulation duration equal to the chronaxie, the tissue can be effectively stimulated with the least amount of energy, minimizing the risk of damage.Rate this question:
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- 24.
X is used to prevent disturbant phenomena that occur between the electrode and the tissue:
- A.
Differential amplifier
- B.
Functional grounding
- C.
Proper selection of electrode material
- D.
Low frequency filters
Correct Answer
C. Proper selection of electrode materialExplanation
The proper selection of electrode material is important in preventing disturbant phenomena that occur between the electrode and the tissue. Different materials have different electrical properties, and selecting the right material can help minimize interference and improve the accuracy of measurements. The choice of electrode material depends on factors such as conductivity, biocompatibility, and stability.Rate this question:
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- 25.
In the space between the electrode and tissue appear:
- A.
Acoustic waves
- B.
Intensive electromagnetic radiation
- C.
Double electric layer
- D.
Charge-repellant forces
- E.
Excitory wave
Correct Answer
C. Double electric layerExplanation
The space between the electrode and tissue forms a double electric layer. This refers to the formation of two layers of charge, one on the surface of the electrode and the other on the surface of the tissue. These layers are formed due to the movement of ions in the surrounding fluid, creating a separation of positive and negative charges. This double electric layer plays a crucial role in the transfer of electrical signals between the electrode and tissue, allowing for effective communication and stimulation.Rate this question:
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- 26.
When is the kinetic energy of a freely oscillating material point the highest?
- A.
When the velocity of the material point is at its maximum
- B.
When the force affecting the material point is at its maximum
- C.
When the force affecting the material point is equal to zero
- D.
When the material point is the furthest away from the equilibrium position
Correct Answer
C. When the force affecting the material point is equal to zeroExplanation
The kinetic energy of a freely oscillating material point is highest when the force affecting the material point is equal to zero. This is because at this point, there is no force acting on the material point to slow it down or change its velocity. As a result, the material point can continue to move with maximum speed and kinetic energy.Rate this question:
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- 27.
Wave strength is measured in:
- A.
J/s
- B.
J/m2
- C.
W/m2
- D.
W*s
Correct Answer
C. W/m2Explanation
Wave strength is measured in watts per square meter (W/m2) because watts is the unit of power and square meter represents the area over which the power is distributed. This measurement is commonly used to quantify the intensity or magnitude of various types of waves, such as electromagnetic waves or sound waves. It provides a standardized way to compare the strength of different waves and assess their impact on the surrounding environment or materials.Rate this question:
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- 28.
Acoustic impedance of a medium is equal to:
- A.
Z = ρv
- B.
Z =
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- C.
Z = ρω
- D.
Z= Lω +
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Correct Answer
A. Z = ρvExplanation
The acoustic impedance of a medium is equal to the product of its density (ρ) and the velocity of sound (v) in that medium. This relationship is derived from the equation Z = ρv, where Z represents acoustic impedance. This equation shows that the acoustic impedance depends on the density and velocity of sound in the medium, indicating how resistant the medium is to the transmission of sound waves.Rate this question:
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- 29.
Which frequency sound waves are the standard for audiometric exams?
- A.
It is based on the individual
- B.
It is a 16 Hz frequency wave
- C.
It is a 20000 Hz frequency wave
- D.
It is a 1000 Hz frequency wave
Correct Answer
D. It is a 1000 Hz frequency waveExplanation
The standard frequency for audiometric exams is typically 1000 Hz. This frequency is commonly used because it falls within the range of human speech, making it a good indicator of a person's ability to hear and understand speech. Additionally, 1000 Hz is a mid-range frequency that is neither too low nor too high, allowing for accurate testing of a person's hearing abilities across different frequencies.Rate this question:
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- 30.
Dynamic viscosity is best described as:
- A.
A force that gives a 1m/s flow speed to a 1m3 volume fluid flowing through a 1m2diameter area
- B.
A fluid's internal resistance force that affects a single unit of fluid area in the direction of the current flow
- C.
A fluid's internal resistance force that affects a unit of fluid layer contact area when the speed gradient is equal to 1
- D.
A measurement describing maximum fluid speed change in a direction perpendicular to the flow direction of the fluid
Correct Answer
C. A fluid's internal resistance force that affects a unit of fluid layer contact area when the speed gradient is equal to 1Explanation
Dynamic viscosity is best described as a fluid's internal resistance force that affects a unit of fluid layer contact area when the speed gradient is equal to 1. This means that dynamic viscosity measures how easily a fluid flows and how resistant it is to deformation. It quantifies the internal friction within a fluid as it flows, with higher viscosity indicating greater resistance to flow. The speed gradient of 1 indicates that the viscosity measurement is taken when the fluid is flowing at a constant rate, without any acceleration or deceleration.Rate this question:
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- 31.
Bernoulli's principle describes:
- A.
The relation between elevating force and the submerged object‘s density
- B.
The relation between absolute temperature and the fluid‘s internal potential energy
- C.
The spreading of mechanical waves in fluids
- D.
The relation between ideal (low viscosity) fluid flow and pressure
Correct Answer
D. The relation between ideal (low viscosity) fluid flow and pressureExplanation
Bernoulli's principle states that in an ideal fluid flow with low viscosity, the pressure of the fluid decreases as the fluid's velocity increases. This principle describes the relationship between fluid flow and pressure, stating that as the fluid flows faster, the pressure it exerts decreases. This principle is commonly used in various applications, such as in the design of airplane wings and the functioning of a venturi meter.Rate this question:
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- 32.
If other conditions remain unchanged, how will the blood flow volume change if a blood vessel‘s radius is decreased 3 times
- A.
No change due to stationary fluid flow equation vS = const
- B.
Volume will decrease 16 times
- C.
Volume will decrease 9 times
- D.
Volume will decrease 81 times
Correct Answer
D. Volume will decrease 81 timesExplanation
According to the Poiseuille's law, the blood flow volume is directly proportional to the fourth power of the blood vessel's radius. Therefore, if the radius is decreased 3 times, the blood flow volume will decrease (3^4) = 81 times.Rate this question:
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- 33.
Stokes' theorem describes:
- A.
Resistance force relation to speed gradient, medium viscosity and pressure difference
- B.
The theorem shows that resistence force depends on medium viscosity, movement speed and object dimensions
- C.
(the relation between the speed of light and ultrasound speed in fluid
- D.
The relation between fluid waves and acoustic waves
Correct Answer
B. The theorem shows that resistence force depends on medium viscosity, movement speed and object dimensionsExplanation
Stokes' theorem describes the relationship between resistance force and various factors such as medium viscosity, movement speed, and object dimensions. It explains that the resistance force experienced by an object moving through a fluid depends on the viscosity of the medium, the speed at which the object is moving, and the dimensions of the object. This theorem helps in understanding and predicting the resistance force experienced by objects in fluid environments.Rate this question:
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- 34.
The Doppler effect is:
- A.
A change in perceived sound frequency due to movement of the sound source
- B.
The spread of sound waves in biological mediums
- C.
The sound signal caused by blood cell movement
- D.
The signal of blood flow registered with a blood pressure monitor
Correct Answer
A. A change in perceived sound frequency due to movement of the sound sourceExplanation
The Doppler effect refers to a change in perceived sound frequency due to the movement of the sound source. This phenomenon occurs when there is relative motion between the source of sound and the observer. As the sound source moves towards the observer, the perceived frequency of the sound waves increases, resulting in a higher pitch. Conversely, when the sound source moves away from the observer, the perceived frequency decreases, resulting in a lower pitch. This effect is commonly experienced when a siren approaches and then passes by, causing a change in the pitch of the sound.Rate this question:
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- 35.
An X-ray tube radiates:
- A.
Only X-rays
- B.
Only X-rays and UV rays
- C.
All of the electromagnetic wave spectrum except for gamma rays
- D.
Only electrons
Correct Answer
C. All of the electromagnetic wave spectrum except for gamma raysExplanation
An X-ray tube is a device that emits X-rays, which are a form of electromagnetic radiation. However, X-ray tubes also emit other types of electromagnetic radiation, such as ultraviolet (UV) rays. Therefore, the correct answer is that an X-ray tube radiates all of the electromagnetic wave spectrum except for gamma rays.Rate this question:
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- 36.
In order for the X-ray tube to radiate shorter X-rays:
- A.
You need to increase the electrical current strength
- B.
You need to increase the electrical resistance (impedance?)
- C.
You need to increase the resolution
- D.
You need to increase the voltage between the anode and the cathode
Correct Answer
D. You need to increase the voltage between the anode and the cathodeExplanation
Increasing the voltage between the anode and the cathode in the X-ray tube will cause the electrons to be accelerated with higher energy. This increased energy will result in the production of shorter wavelength X-rays, as wavelength is inversely proportional to energy. Therefore, increasing the voltage will lead to the emission of shorter X-rays.Rate this question:
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- 37.
Bremsstrahlung X-Rays (braking radiation x-rays) form due to:
- A.
Photon braking in the X-ray tube
- B.
Electron braking on the surface of the anode
- C.
Electron leaps between atom‘s electron layers
- D.
Electron braking on the surface of the cathode
Correct Answer
B. Electron braking on the surface of the anodeExplanation
Bremsstrahlung X-rays are formed due to electron braking on the surface of the anode. When high-speed electrons are decelerated or slowed down by the electric field near the anode, they emit X-ray photons. This process is known as bremsstrahlung radiation. The energy of the emitted X-rays depends on the energy lost by the electrons during braking. Therefore, the correct answer is electron braking on the surface of the anode.Rate this question:
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- 38.
When the wave length increases, photon energy:
- A.
Does not change
- B.
Decreases
- C.
Increases
- D.
Photon energy is not related to wave length
Correct Answer
B. DecreasesExplanation
When the wavelength of a wave increases, the photon energy decreases. This is because photon energy is inversely proportional to wavelength. As the wavelength increases, the frequency decreases, and since photon energy is directly proportional to frequency, it also decreases. Therefore, when the wavelength increases, the photon energy decreases.Rate this question:
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- 39.
X-rays ionise material due to:
- A.
Rayleigh scattering
- B.
X ray luminescence
- C.
Photoelectric effect
- D.
Impact ionization
Correct Answer
C. Photoelectric effectExplanation
The correct answer is the photoelectric effect. X-rays ionize material by knocking out inner shell electrons, resulting in the ejection of electrons from the atom. This occurs when X-ray photons transfer their energy to the electrons, causing them to be released from the atom. The photoelectric effect is a significant process in X-ray imaging and is responsible for the contrast seen in X-ray images.Rate this question:
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- 40.
Radioactive decay radiates:
- A.
X-ray and gamma ray photons
- B.
Gamma photons, Helium nuclei, electrons, positrons
- C.
UV rays
- D.
Protons and neutrons
Correct Answer
B. Gamma photons, Helium nuclei, electrons, positronsExplanation
Radioactive decay is the process in which an unstable atomic nucleus emits radiation in order to become more stable. This radiation can take the form of gamma photons, which are high-energy electromagnetic waves, as well as Helium nuclei, electrons, and positrons. Gamma photons carry a lot of energy and are capable of penetrating matter, while Helium nuclei, electrons, and positrons are charged particles that can also be emitted during radioactive decay. UV rays, protons, and neutrons are not typically emitted during radioactive decay.Rate this question:
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- 41.
During radioactive decay, after 4 halflives the amount of non-disintegrated nuclei left is:
- A.
2 times less than at the beginning
- B.
4 times less than at the beginning
- C.
16 times less than at the beginning
- D.
32 times less than at the beginning
Correct Answer
C. 16 times less than at the beginningExplanation
During radioactive decay, the number of non-disintegrated nuclei decreases by half after each half-life. After 4 half-lives, the number of non-disintegrated nuclei would have decreased by a factor of 2^4, which is equal to 16. Therefore, the amount of non-disintegrated nuclei left is 16 times less than at the beginning.Rate this question:
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- 42.
Dark-field microscopy utilises:
- A.
Dark law/principle
- B.
Coherent light scattering principle
- C.
Uncoherent light scattering principle
- D.
Light absorbtion principle
Correct Answer
B. Coherent light scattering principleExplanation
Dark-field microscopy utilizes the coherent light scattering principle. In dark-field microscopy, a special condenser is used to direct light at an angle to the sample, causing the light to scatter. This scattered light is then collected by the objective lens, while the direct light is blocked. The scattered light creates a bright image against a dark background, allowing for enhanced visualization of small particles or structures in the sample. Coherent light scattering refers to the scattering of light waves in a way that maintains their phase relationship, resulting in constructive interference and a clear, contrasted image.Rate this question:
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- 43.
Due to light dispersion:
- A.
Red light refracts more than yellow light in material
- B.
Blue light refracts more than yellow light in material
- C.
Yellow light refracts more than blue light in material
- D.
Green light refracts more than orange light in material
Correct Answer
B. Blue light refracts more than yellow light in materialExplanation
When light passes through a material, it bends or refracts due to the change in its speed. This bending of light is different for different colors of light, which is known as dispersion. Blue light has a shorter wavelength than yellow light, and shorter wavelengths tend to refract more than longer wavelengths. Therefore, blue light refracts more than yellow light in a material.Rate this question:
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- 44.
Absolute refractive index is:
- A.
The ratio of light speed in material and in vacuum
- B.
Light refraction angle
- C.
The ratio of light speed in vacuum and material
- D.
The ratio of light speed in material 1 and material 2
Correct Answer
A. The ratio of light speed in material and in vacuumExplanation
The absolute refractive index is defined as the ratio of the speed of light in a given material to the speed of light in a vacuum. This index determines how much the light is bent or refracted when it passes from one medium to another. It is a fundamental property of a material and is used to calculate the angle of refraction when light travels through different substances.Rate this question:
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- 45.
Na+/K+ pump ion transportation is:
- A.
Passive, because it doesn‘t require energy
- B.
Active, because it uses the cell‘s energy resources
- C.
Passive, because the ions are transported against the concentration gradient
- D.
Active, because charged particles are transported through the membrane
Correct Answer
B. Active, because it uses the cell‘s energy resourcesExplanation
The Na+/K+ pump is considered active because it utilizes the cell's energy resources. This pump actively transports sodium ions out of the cell and potassium ions into the cell, against their concentration gradients. This process requires the hydrolysis of ATP to provide the energy needed for the pump to function. Therefore, the Na+/K+ pump is an example of active transport, as it requires energy expenditure by the cell.Rate this question:
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- 46.
How are the electric and diffusive forces affecting K+ directed when the cell is at rest?
- A.
Electric force is directed inwards to the cell, diffusive – outwards
- B.
These forces are not active when the cells is at rest
- C.
When the cell is at rest only the diffusive force is active – directed outwards
- D.
Both these forces are directed inwards
Correct Answer
A. Electric force is directed inwards to the cell, diffusive – outwardsExplanation
When the cell is at rest, the electric force is directed inwards towards the cell, while the diffusive force is directed outwards. This means that the electric force is pulling potassium ions (K+) towards the inside of the cell, while the diffusive force is pushing the potassium ions outwards. These forces are active even when the cell is at rest, and their opposing directions create an equilibrium where the movement of potassium ions is balanced.Rate this question:
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- 47.
Cell action potential is:
- A.
Change in membrane potential when an excitory/stimulatory cell is affected with only electric stimuli
- B.
Change in membrane potential when an excitory/stimulatory cell is affected with over-threshold stimuli
- C.
The membrane potential of an unexcited cell
- D.
Change in membrane potential when a cell is affected with under-threshold stimuli
Correct Answer
B. Change in membrane potential when an excitory/stimulatory cell is affected with over-threshold stimuliExplanation
Cell action potential refers to the change in membrane potential that occurs when an excitatory/stimulatory cell is affected by stimuli that exceed the threshold. This means that the cell is being stimulated with a strong enough signal to trigger an action potential, causing a rapid change in the cell's membrane potential. This change in membrane potential is essential for the transmission of signals within the nervous system and is a fundamental process in the functioning of neurons.Rate this question:
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- 48.
How is repolarisation explained?
- A.
Sodium ions leaving the cell due to the Sodium/Potassium pump
- B.
Sodium ions entering the cells due to sudden membrane permeability to Sodium ions increase
- C.
A decrease in membrane permeability to Potassium ions
- D.
Potassium ions leaving the cell due to increased membrane permeability to Potassium ions
Correct Answer
A. Sodium ions leaving the cell due to the Sodium/Potassium pumpExplanation
During repolarization, the cell returns to its resting state after depolarization. This is achieved by the Sodium/Potassium pump, which actively transports three sodium ions out of the cell in exchange for two potassium ions entering the cell. Therefore, the correct explanation is that repolarization is explained by sodium ions leaving the cell due to the Sodium/Potassium pump.Rate this question:
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- 49.
λ in the electronic stimulus spread equation is:
- A.
Distance at which potential is e (e=2.7) times weaker
- B.
A measurement inverse to the distance at which potential is 2x weaker
- C.
Light wave length
- D.
The distance at which potential disappears
Correct Answer
A. Distance at which potential is e (e=2.7) times weakerExplanation
The correct answer is "distance at which potential is e (e=2.7) times weaker." This means that the value of lambda in the electronic stimulus spread equation represents the distance at which the potential becomes 2.7 times weaker than its initial value.Rate this question:
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- 50.
How does the myelin sheath of an axon affect the speed of the spread of an excitory signal?
- A.
Prevents spread
- B.
Decreases the speed
- C.
Increases the speed
- D.
Does not affect speed
Correct Answer
C. Increases the speedExplanation
The myelin sheath of an axon acts as an insulating layer, covering the axon and allowing for faster transmission of electrical signals. It does this by preventing the leakage of ions and reducing the capacitance of the axon, which results in faster transmission of the signal. Therefore, the myelin sheath increases the speed of the spread of an excitatory signal.Rate this question:
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