Physics Key To Success
- 1.
Thank you for doing my test, byebye
- 2.
Which of these are dispersions (dispersed systems)? (What do we call dispersed systems?)
- A.
Salt solutions
- B.
Materials which disperse light)
- C.
(Materials which disperse sound waves)
- D.
(Suspensions, emulsions, aerosols, other mixtures)
Correct Answer
D. (Suspensions, emulsions, aerosols, other mixtures) -
- 3.
(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 fluctuation)Explanation
When alternating current is applied to live tissues, the phenomenon of ion fluctuation is observable. Alternating current causes the ions within the live tissues to move back and forth, resulting in their fluctuation. This movement of ions is due to the changes in the direction and magnitude of the electric field produced by the alternating current. Ion fluctuation is an important aspect to consider in various biological processes, such as nerve conduction and muscle contraction.Rate this question:
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- 4.
(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.
(Electrostatic induction)
- E.
(skin) (Skin effect)
Correct Answer
C. (Translational motion of ions and the redistribution of their concentrations)Explanation
When direct current is applied to live tissues, the phenomenon of translational motion of ions and the redistribution of their concentrations can be observed. Direct current causes ions to move in a specific direction, leading to a redistribution of ions within the tissue. This movement of ions is important for various physiological processes in the body, such as nerve conduction and muscle contraction.Rate this question:
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- 5.
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 frequency of the current flowing through the tissue
- D.
The relation of the impedance and the strength of the current flowing through the tissu
- E.
The relation of the impedance and the frequency of the magnetic field affecting the tissu
Correct Answer
C. The relation of the impedance and the frequency of the current flowing through the tissueExplanation
The correct answer is the relation of the impedance and the frequency of the current flowing through the tissue. Impedance is the measure of opposition to the flow of current in a tissue. It is influenced by the frequency of the current passing through the tissue. Different tissues have different impedance values at different frequencies. This relationship is important in medical applications such as impedance spectroscopy, where the impedance of tissues is measured at different frequencies to assess their physiological properties or detect abnormalities.Rate this question:
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- 6.
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 observable phenomenon is the rotation of paramagnetic particles along the field's line of force. Paramagnetic particles have unpaired electrons, which align with the magnetic field causing them to rotate in the same direction as the field. This phenomenon is commonly observed in magnetic resonance imaging (MRI) where the alignment of paramagnetic particles provides detailed images of the internal structures of the body.Rate this question:
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- 7.
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 particles when affected by an electric field)
- D.
(The movement of dispersive media when affected by an electric field)
Correct Answer
C. (The movement of dispersive particles when affected by an electric field)Explanation
Electrophoresis refers to the movement of dispersive particles when they are influenced by an electric field. This phenomenon is commonly used in laboratories to separate and analyze different molecules based on their size and charge. By applying an electric field, charged particles will migrate towards the electrode with the opposite charge, allowing for the separation and identification of specific components within a mixture.Rate this question:
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- 8.
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 can cause a change in cell polarity or polarization. This means that the electric charges within the cells are rearranged or redistributed, leading to a shift in the overall charge distribution within the cells. This phenomenon can have various effects on the functioning of the cells and their interactions with other cells or external stimuli.Rate this question:
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- 9.
What is observed in tissues due to the Hall effect?
- A.
(Cell polarization)
- B.
(The production of a voltage difference across the walls of a blood vessel
- C.
(Ion fluctuation)
- D.
Movement of paramagnetic particles
Correct Answer
B. (The production of a voltage difference across the walls of a blood vesselExplanation
The Hall effect refers to the production of a voltage difference across the walls of a blood vessel. This phenomenon occurs when an electric current passes through a conductor in the presence of a magnetic field perpendicular to the current flow. The magnetic field causes the charged particles in the blood vessel to experience a force, resulting in the separation of positive and negative charges and the generation of a voltage difference. This effect is commonly observed in tissues and is important for various physiological processes, such as blood flow regulation.Rate this question:
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- 10.
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
When a static electric field affects live tissues, the phenomenon that is observable is electrostatic induction. Electrostatic induction refers to the redistribution of electric charges within an object or a material in response to the presence of an external electric field. In this case, the static electric field causes the redistribution of charges within the live tissues, leading to observable effects.Rate this question:
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- 11.
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.
Electromagnetic inductio
- D.
Ion fluctuation)
Correct Answer
C. Electromagnetic inductioExplanation
When an alternating magnetic field affects live tissues, the phenomenon that is observable is electromagnetic induction. This is because the changing magnetic field induces an electric current in the tissues, which can be measured and observed. The other options, such as rotation of polar particles, paramagnetic particle fluctuation, and ion fluctuation, do not accurately describe the specific phenomenon that occurs when an alternating magnetic field affects live tissues.Rate this question:
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- 12.
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 of an ion in a 1 V/m electric field)
- C.
(the speed that an ion gains when a 1A electric current is applied)
- D.
(the speed of an ion in a 1 A/m magnetic field)
Correct Answer
B. (the speed of an ion in a 1 V/m electric field)Explanation
Electrical (ion) mobility is best described as the speed of an ion in a 1 V/m electric field. This means that it measures how quickly an ion will move when subjected to an electric field with a strength of 1 volt per meter. It is important to note that electrical mobility is specific to ions and is not related to the speed of an ion in a magnetic field or the speed gained when a 1A electric current is applied.Rate this question:
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- 13.
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 a shift in the magnetic moment orientation of atom nuclei)
- C.
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)
- D.
A sudden increase in the amplitude of nuclei fluctation (oscillation) of atoms when affected with a constant magnetic field and certan frequency electromagnetic waves)
Correct Answer
B. 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
This answer correctly describes nuclear magnetic resonance (NMR) as the absorption of certain frequency electromagnetic waves in material when affected by a constant magnetic field. This absorption is due to a shift in the magnetic moment orientation of atom nuclei. NMR is a technique used to study the properties of atomic nuclei and their surrounding environment, providing valuable information about molecular structure and dynamics.Rate this question:
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- 14.
(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.
D) pm = (I*S)/p
- E.
Pm = S/I
Correct Answer
A. pm = I*SExplanation
The given equation, pm = I*S, states that 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 equation follows the basic principle of magnetism, where the magnetic moment is directly proportional to the current and the area enclosed by the current loop. Therefore, the correct answer is pm = I*S.Rate this question:
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- 15.
Which of these correctly expresses the main condition of NMR
- A.
Hv = gbrβbrI
- B.
Hv = gbremfβbr
- C.
Hv = gbrβbrmbr
- D.
Hv = gbrB
- E.
Hv = gbrβbrB
Correct Answer
E. Hv = gbrβbrB -
- 16.
The Nyquist Theorem states that:
- A.
a continuous-time signal is only defined at certain moments in time
- B.
The sampling frequency can‘t be lower than 2x the signal frequency
- C.
A continuous-time signal cannot be described
- D.
Discrete-time signals do not appear during biological processes
Correct Answer
B. The sampling frequency can‘t be lower than 2x the signal frequencyExplanation
The Nyquist Theorem states that the sampling frequency must be at least twice the signal frequency in order to accurately reconstruct the original continuous-time signal from its discrete samples. This is because the highest frequency component in the signal is represented by the Nyquist frequency, which is half the sampling frequency. If the sampling frequency is lower than 2 times the signal frequency, the Nyquist frequency will be lower than the highest frequency component in the signal, leading to aliasing and loss of information in the reconstructed signal.Rate this question:
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- 17.
Paramagnetic material is best described as a material, with particles that have:________
Correct Answer
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 can align with an external magnetic field. However, unlike ferromagnetic materials, the magnetic moments in paramagnetic materials do not align spontaneously and persistently in the absence of an external field. Instead, they only align temporarily when exposed to a magnetic field and lose their alignment once the field is removed. This property makes paramagnetic materials weakly attracted to magnetic fields, exhibiting a weak magnetic response.Rate this question:
- 18.
(EKG)? (Electrocardiogram (ECG) is best described as:
- A.
The evaluation of mechanical heart function)
- B.
(a measurement of heart function induced change in potential difference between two areas of the body)
- C.
The spread of an excitory signal towards the extremities)
- D.
(electrical heart function
Correct Answer
B. (a measurement of heart function induced change in potential difference between two areas of the body) -
- 19.
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 used to assess the electrical conduction system of the heart and diagnose any abnormalities. Phonocardiogram measures the sounds of the heart, seismocardiogram measures the vibrations of the heart, and arterial blood pressure curve measures the pressure of blood in the arteries.Rate this question:
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- 20.
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 positive and negative charges in a dipole model of the heart refer to the non-excited and excited heart areas. In the heart, electrical activity occurs when certain areas become excited and generate electrical signals, while other areas remain non-excited. This creates a dipole, with one area having a positive charge and the other having a negative charge. This electrical activity is crucial for the proper functioning of the heart, as it coordinates the contraction and relaxation of the heart muscles, allowing for the pumping of blood.Rate this question:
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- 21.
The electrical irritability law describes the relation between
- A.
The maximum irritation current strength and irritation duration
- B.
(the lowest possible irritation constant 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
- F.
(the lowest possible irritation current strength still able to irritate and irritation duration)
Correct Answer
F. (the lowest possible irritation current strength still able to irritate and irritation duration)Explanation
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 the irritation. This means that there is a minimum threshold of current strength required to elicit a response, and the length of time the irritation lasts is also a factor. The law does not describe the relationship between irritation current strength and voltage, or the lowest and maximum irritation current strength. It also does not involve the terms rheobase and chronaxie.Rate this question:
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- 22.
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
- E.
The lowest constanst strength still able to irritate
Correct Answer
C. The lowest current strength still able to irritateExplanation
Rheobase refers to the minimum current strength that is still capable of causing irritation. It represents the threshold at which a stimulus is just strong enough to elicit a response. It is the lowest current strength that can still produce an irritant effect, indicating that any current below this threshold would not be able to cause irritation.Rate this question:
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- 23.
Chronaxie is
- A.
(the shortest duration of irritation when strength is equal to rheobase)
- B.
Highest possible irritation current strength
- C.
Shortest duration of irritation when constant strength is equal to 2x rheobase
- D.
Shortest duration of irritation when current strength is equal to 2x rheobase
- E.
Longest 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 is the shortest duration of irritation when the current strength is equal to 2x rheobase. It represents the minimum amount of time required for a stimulus with double the strength of rheobase to elicit a response. This means that chronaxie is a measure of the excitability of a nerve or muscle, with a shorter chronaxie indicating a higher level of excitability.Rate this question:
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- 24.
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 2x chronaxie
- D.
The lowest amount of energy is used when stimulation duration is equal to chronaxie
Correct Answer
D. 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 chronaxie. Chronaxie refers to the minimum duration of an electrical pulse that is needed to produce a response from a tissue or cell. This principle suggests that by using a stimulation duration equal to 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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- 25.
X is used to prevent disturbant phenomena that occur between the electrode and the tissue:
- A.
Proper selection of electrode material
- B.
(functional grounding
- C.
Differential amplifier
- D.
Low frequency filters
Correct Answer
A. Proper selection of electrode materialExplanation
The proper selection of electrode material is used to prevent disturbant phenomena that occur between the electrode and the tissue. Different materials have different electrical properties, and selecting the right material can minimize interference and ensure accurate measurements. The chosen material should have good conductivity, low impedance, and be biocompatible to minimize tissue damage and irritation. By selecting the appropriate electrode material, the risk of disturbances such as noise, artifacts, and signal degradation can be reduced, leading to more reliable and accurate measurements in medical or research settings.Rate this question:
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- 26.
In the space between the electrode and tissue appear:
- A.
Acoustic waves
- B.
Intensive electromagnetic radiation
- C.
Excitory wave
- D.
Double electric layer
Correct Answer
D. Double electric layerExplanation
The space between the electrode and tissue can form a double electric layer. This occurs when ions in the tissue and electrode create a separation of charge, resulting in two layers of opposite charges. This double electric layer plays a crucial role in various electrochemical processes, such as ion transport and electrode reactions.Rate this question:
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- 27.
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 equal to zero
- C.
When the force affecting the material point is at its maximum
- D.
when the material point is the furthest away from the equilibrium position
Correct Answer
B. When the force affecting the material point is equal to zeroExplanation
The correct answer is when the force affecting the material point is equal to zero. When the force on a material point is zero, it means that there is no external force acting on it, and therefore no work is being done on the point. According to the work-energy theorem, the work done on an object is equal to the change in its kinetic energy. If no work is being done on the material point, its kinetic energy remains constant. Therefore, the highest kinetic energy occurs when the force on the material point is equal to zero.Rate this question:
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- 28.
Wave strength is measured in:
- A.
J/s
- B.
W/m2
- C.
W*s
- D.
J/m2
Correct Answer
B. W/m2Explanation
Wave strength is measured in watts per square meter (W/m2). This unit represents the amount of energy transferred by a wave per unit area. It is commonly used to measure the intensity or power density of various types of waves, such as electromagnetic waves or sound waves. The higher the value of W/m2, the stronger the wave.Rate this question:
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- 29.
Acoustic impedance of a medium is equal to________
Correct Answer
Z=pvExplanation
The acoustic impedance of a medium is equal to the product of its density (p) and the velocity (v) of sound waves in that medium. This relationship is represented by the equation Z = pv. Acoustic impedance is a measure of how a medium resists the transmission of sound waves, and it is determined by the physical properties of the medium such as its density and the speed at which sound travels through it.Rate this question:
- 30.
Which frequency sound waves are the standard for audiometric exams
- A.
It is a 1000 Hz frequency wave
- B.
It is a 20000 MHz frequency wave
- C.
(it is a 16 MHz frequency wav
- D.
It is a 1000 MHz frequency wave
- E.
It is based on the individual
Correct Answer
A. It is a 1000 Hz frequency waveExplanation
Audiometric exams are conducted to measure a person's hearing ability. The standard frequency for these exams is typically 1000 Hz. This frequency is chosen because it falls within the range of human speech sounds, making it an ideal frequency to test a person's ability to hear and understand speech. Other frequencies, such as 20000 MHz or 16 MHz, are not commonly used in audiometric exams as they are either too high or too low for human hearing. The answer "it is a 1000 Hz frequency wave" aligns with the standard frequency used in audiometric exams.Rate this question:
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- 31.
Dynamic viscosity is best described as
- A.
A fluid's internal resistance force that affects a unit of fluid layer contact area when the speed gradient is equal to 1
- B.
A force that gives a 1m/s flow speed to a 1m3 volume fluid flowing through a 1m2diameter area
- C.
A fluid's internal resistance force that affects a single unit of fluid area in the direction of the current flow
- D.
A fluid's internal resistance force that affects a unit of fluid layer contact area when the speed gradient is equal to 0
- E.
A fluid's external resistance force that affects a unit of fluid layer contact area when the speed gradient is equal to 1
Correct Answer
A. 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 the fluid's resistance to flow when there is a difference in velocity between different layers of the fluid. When the speed gradient is equal to 1, it indicates that there is a linear change in velocity across the fluid layers, and the dynamic viscosity determines the magnitude of the internal resistance force experienced by the fluid.Rate this question:
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- 32.
Bernoulli's principle describes:
- A.
(the relation between high viscosity fluid flow and pressure
- B.
(the relation between ideal (low viscosity) fluid flow and pressure)
- C.
The spreading of mechanical waves in fluids
- D.
The relation between elevating force and the submerged object‘s density
Correct Answer
B. (the relation between ideal (low viscosity) fluid flow and pressure)Explanation
Bernoulli's principle describes the relationship between ideal (low viscosity) fluid flow and pressure. According to this principle, as the speed of a fluid increases, its pressure decreases, and vice versa. This principle is based on the conservation of energy in fluid flow, stating that the total energy of a fluid remains constant along a streamline. It is commonly observed in various phenomena, such as the lift generated by an airplane wing, the flow of blood in arteries, and the operation of a Venturi tube.Rate this question:
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- 33.
If other conditions remain unchanged, how will the blood flow volume change if a blood vessel‘s radius is decreased 3 times
- A.
Volume will decrease 81 times
- B.
Volume will decrease 16 times
- C.
No change due to stationary fluid flow equation vS = const
- D.
Volume will decrease 9 times
- E.
Volume will increase 81 times
- F.
Volume will increase 16 times
- G.
Slightly more blood flow volume due to D=n*u*t*z
Correct Answer
A. Volume will decrease 81 timesExplanation
When the radius of a blood vessel is decreased, the blood flow volume will decrease 81 times. This is because the volume of blood flow is directly proportional to the fourth power of the radius according to Poiseuille's law. Therefore, when the radius is decreased by a factor of 3, the volume will decrease by a factor of (1/3)^4 = 1/81.Rate this question:
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- 34.
Stokes' theorem describes
- A.
Resistance force relation to speed gradient, medium viscosity and pressure difference
- B.
The relation between the speed of light and ultrasound speed in fluid) d) (the relation between fluid waves and acoustic waves
- C.
The theorem shows that resistence force depends on medium viscosity, movement speed and object dimensions
- D.
The theorem shows that viscocity force depends on medium resistance, movement speed and object dimensions
Correct Answer
C. The theorem shows that resistence force depends on medium viscosity, movement speed and object dimensionsExplanation
Stokes' theorem describes the relationship between the resistance force and the medium viscosity, movement speed, and object dimensions. This means that the resistance force experienced by an object moving through a fluid depends on the viscosity of the medium, the speed of movement, and the dimensions of the object.Rate this question:
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- 35.
The Doppler effect is:
- A.
The spread of sound waves in biological mediums
- B.
The sound signal caused by blood cell movement
- C.
The signal of blood flow registered with a blood pressure monitor
- D.
A change in perceived sound frequency due to movement of the sound source
Correct Answer
D. A change in perceived sound frequency due to movement of the sound sourceExplanation
The Doppler effect refers to the change in perceived sound frequency that occurs when there is relative motion between the sound source and the observer. This phenomenon is observed in everyday situations, such as when a car passes by and the sound of its horn appears to change pitch. The frequency of the sound waves appears higher when the source is approaching the observer and lower when it is moving away. This effect is not related to the spread of sound waves in biological mediums, the sound signal caused by blood cell movement, or the signal of blood flow registered with a blood pressure monitor.Rate this question:
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- 36.
An X-ray tube radiates:
- A.
Only electrons
- B.
(only X-rays and UV rays
- C.
Only X-rays
- D.
All of the electromagnetic wave spectrum except for gamma rays
Correct Answer
D. All of the electromagnetic wave spectrum except for gamma raysExplanation
An X-ray tube is a device that produces X-rays by accelerating electrons through a high voltage. When electrons strike a metal target, X-rays are generated. However, in addition to X-rays, the process also produces a range of other electromagnetic waves, including ultraviolet (UV) rays. Therefore, an X-ray tube radiates all of the electromagnetic wave spectrum except for gamma rays.Rate this question:
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- 37.
In order for the X-ray tube to radiate shorter X-rays:
- A.
You need to decrease the voltage between the anode and the cathode
- B.
(you need to increase the electrical resistance (impedance?)
- C.
You need to increase the voltage between the anode and the cathode
- D.
(you need to decrease the resolution
Correct Answer
C. You need to increase the voltage between the anode and the cathodeExplanation
To radiate shorter X-rays, the voltage between the anode and the cathode needs to be increased. Increasing the voltage will result in higher energy electrons being accelerated towards the anode, causing them to collide with greater force. This increased collision energy leads to the emission of shorter wavelength X-rays, as wavelength is inversely proportional to energy. Therefore, increasing the voltage between the anode and the cathode is necessary to produce shorter X-rays.Rate this question:
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- 38.
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 cathode
- C.
Electron braking on the surface of the anode
Correct Answer
C. Electron braking on the surface of the anodeExplanation
Bremsstrahlung X-Rays, also known as braking radiation X-rays, form due to the electron braking on the surface of the anode. When high-speed electrons are decelerated or slowed down by the electric field near the positively charged anode, they emit X-ray photons. This process is called bremsstrahlung, which means "braking radiation" in German. The energy of the emitted X-rays depends on the energy loss of the electrons during braking. Therefore, electron braking on the surface of the anode is responsible for the formation of bremsstrahlung X-rays.Rate this question:
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- 39.
When the wave length increases, photon energy:________
Correct Answer
decreasesExplanation
When the wavelength of a wave increases, the photon energy decreases. This is because the energy of a photon is inversely proportional to its wavelength. As the wavelength increases, the frequency decreases, and since energy is directly proportional to frequency, the photon energy decreases. In other words, longer wavelengths correspond to lower energy photons.Rate this question:
- 40.
X-rays ionise material due to________
Correct Answer
photoelectric effectExplanation
X-rays ionize material due to the photoelectric effect. When X-rays interact with atoms, they can transfer enough energy to remove tightly bound electrons from their orbits. This process is known as the photoelectric effect. The energy of the X-ray photons is absorbed by the atoms, causing the ejection of electrons and the creation of positively charged ions. This ionization effect is important in various applications of X-rays, such as medical imaging and industrial inspections.Rate this question:
- 41.
Radioactive decay radiates
- A.
Gamma photons
- B.
Positrons
- C.
Protons
- D.
gamma ray photons
- E.
Xray photons
- F.
Electrons
- G.
Neutrons
- H.
Helium nuclei
Correct Answer(s)
A. Gamma photons
B. Positrons
F. Electrons
H. Helium nucleiExplanation
Radioactive decay is the process in which an unstable atomic nucleus releases energy in the form of radiation. This radiation can take different forms, including gamma photons, positrons, electrons, and helium nuclei. Gamma photons are high-energy electromagnetic waves, while positrons are positively charged particles, electrons are negatively charged particles, and helium nuclei are made up of two protons and two neutrons. These various types of radiation are emitted during radioactive decay as the unstable nucleus seeks a more stable configuration.Rate this question:
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- 42.
Dark-field microscopy utilises:
- A.
Dark law/principle
- B.
Light absorbtion principle
- C.
Uncoherent light scattering principle
- D.
Coherent light scattering principle
Correct Answer
D. 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 specimen. This causes the light to scatter off the specimen, while the direct light is blocked. The scattered light is then collected by the objective lens and forms the image. This technique enhances the visibility of transparent or low-contrast specimens, allowing for better visualization of fine details and structures.Rate this question:
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- 43.
During radioactive decay, after 4 halflives the amount of nondisintegrated nuclei left is:
- A.
(2 times less than at the beginning)
- B.
(4 times less than at the beginning)
- C.
(12 times less than at the beginning)
- D.
(16 times less than at the beginning)
- E.
(32 times less than at the beginning
- F.
None is correct
Correct Answer
D. (16 times less than at the beginning)Explanation
During radioactive decay, the amount of nondisintegrated nuclei decreases by half after each half-life. After 4 half-lives, the amount of nondisintegrated nuclei left would be reduced by a factor of 2^4, which is equal to 16. Therefore, the correct answer is that the amount of nondisintegrated nuclei left is 16 times less than at the beginning.Rate this question:
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- 44.
Due to light dispersion:
- A.
Red light refracts more than yellow light in material
- B.
Green light refracts more than orange light in material
- C.
(yellow light refracts more than blue light in material
- D.
Blue light refracts less than yellow light in material
- E.
Blue light refracts more than yellow light in material
Correct Answer
E. Blue light refracts more than yellow light in materialExplanation
This answer is correct because it states that blue light refracts more than yellow light in material. This is due to the phenomenon of light dispersion, where different colors of light bend or refract at different angles when passing through a material. Blue light has a shorter wavelength than yellow light, causing it to refract more when entering a material.Rate this question:
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- 45.
Absolute refractive index is
- A.
The ratio of light speed in material and in vacuum
- B.
The ratio of light speed in material 1 and material 2
- C.
Light refraction angle in medium and in vacuum
- D.
Absolute refractive index is the refractive index of a medium in vacuum
Correct Answer(s)
A. The ratio of light speed in material and in vacuum
D. Absolute refractive index is the refractive index of a medium in vacuumExplanation
The correct answer is "the ratio of light speed in material and in vacuum". Absolute refractive index is a measure of how much a material slows down the speed of light compared to its speed in a vacuum. It is calculated by dividing the speed of light in the material by the speed of light in a vacuum. This value is a fundamental property of the material and is used to determine how light will behave when passing through it.Rate this question:
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- 46.
Na+/K+ pump ion transportation is:
- A.
Passive, because it doesn‘t require energy
- B.
Passive, because the ions are transported against the concentration gradient
- C.
Active, because charged particles are transported through the membrane
- D.
Active, because it uses the cell‘s energy resources
Correct Answer
D. Active, because it uses the cell‘s energy resourcesExplanation
The Na+/K+ pump is considered active because it uses 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 use of ATP, which provides the necessary energy for the pump to function. As a result, the Na+/K+ pump helps maintain the electrochemical gradient across the cell membrane, which is essential for various cellular processes such as nerve impulse transmission and muscle contraction.Rate this question:
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- 47.
How are the electric and diffusive forces affecting K+ directed when the cell is at rest
- A.
when the cell is at rest only the diffusive force is active – directed outwards
- B.
Both these forces are directed inwards
- C.
These forces are not active when the cells is at rest
- D.
Electric force is directed inwards to the cell, diffusive – outwards
Correct Answer
D. 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 K+ ions towards the inside of the cell, while the diffusive force is pushing them outwards. This balance between the two forces is important for maintaining the resting membrane potential of the cell.Rate this question:
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- 48.
Cell action potential is:
- A.
Change in membrane potential when a cell is affected with under-threshold stimuli
- B.
Change in membrane potential when an excitory/stimulatory cell is affected with only electric stimul
- C.
The membrane potential of an unexcited cell
- D.
Change in membrane potential when an excitory/stimulatory cell is affected with over-threshold stimuli
Correct Answer
D. Change in membrane potential when an excitory/stimulatory cell is affected with over-threshold stimuliExplanation
An action potential is a change in the membrane potential of a neuron or muscle cell. It occurs when the cell is stimulated with an electrical signal that reaches a certain threshold. When this threshold is surpassed, the cell undergoes a rapid depolarization and repolarization, resulting in the generation and propagation of an action potential along the cell membrane. This allows for the transmission of signals within the nervous system. Therefore, the correct answer is "Change in membrane potential when an excitatory/stimulatory cell is affected with over-threshold stimuli."Rate this question:
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- 49.
How is repolarisation explained?
- A.
Sodium ions leaving the cell due to the Sodium/Potassium pump
- B.
Potassium ions leaving the cell due to increased membrane permeability to Potassium ions
- C.
A decrease in membrane permeability to Potassium ions
- D.
Sodium ions entering the cells due to sudden membrane permeability to Sodium ions increase
Correct Answer
B. Potassium ions leaving the cell due to increased membrane permeability to Potassium ionsExplanation
During repolarization, the cell returns to its resting state after depolarization. This is achieved by allowing potassium ions to leave the cell through increased membrane permeability to potassium ions. As the membrane becomes more permeable to potassium ions, they flow out of the cell, leading to repolarization. This process helps restore the negative charge inside the cell and prepares it for the next action potential.Rate this question:
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- 50.
Vx = V0e-x/λ ;: (λ in the electronic stimulus spread equation is:
- A.
Distance at which potential is e (e=2.5) times weaker
- B.
Distance at which potential is e (e=2.6) times weaker
- C.
Distance at which potential is e (e=2.8) times weaker
- D.
Distance at which potential is e (e=2.7) times weaker
- E.
The distance at which potential disappears
Correct Answer
D. 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". In the given equation, Vx = V0e-x/λ, the value of λ represents the distance at which the potential is e (e=2.7) times weaker. This means that as the distance increases, the potential decreases exponentially according to the given equation.Rate this question:
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