Test Physics Num 1

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.

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.

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.

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.

The strength of a standing wave is equal to 0. This means that there is no net transfer of energy in a standing wave. In a standing wave, the wave is trapped between two points and oscillates back and forth without any overall displacement. Therefore, the strength, or the amplitude, of the standing wave is zero.

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.

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.

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.

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.

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.

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.

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.

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.

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.

The correct answer explains that the main difference between Newtonian and Non-Newtonian fluids lies in their dynamic viscosity coefficient. For Newtonian fluids, this coefficient does not depend on flow conditions and remains static. On the other hand, for Non-Newtonian fluids, the dynamic viscosity coefficient is dynamic and varies depending on the flow conditions. This means that the viscosity of Non-Newtonian fluids can change with the rate of flow or the amount of shear stress applied.

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).

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

The correct answer is M=p*E*sin α. This equation represents the torque (M) experienced by a polar particle (molecule) when placed in an electric field (E) at an angle (α) to the field. The torque is proportional to the dipole moment (p) of the particle and the magnitude of the electric field, and it is also affected by the angle between the dipole moment and the electric field direction. Therefore, M=p*E*sin α accurately describes the interaction between an electric field and a polar particle.

An electrode is classified as a passive direct sensor because it does not actively generate a signal or require external power to function. Instead, it detects and measures electrical activity or signals in the environment or a biological system. Electrodes are typically made of conductive materials and are used in various applications such as electrocardiography (ECG), electroencephalography (EEG), and electrochemical analysis. They act as interfaces between the system being measured and the measuring instrument, allowing for the detection and recording of electrical signals without actively influencing the system.

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.

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.

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.

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.

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.

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.

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.

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.

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.

During radioactive decay, the amount of nuclei left decreases by half after each half-life. Therefore, after 6 half-lives, the amount of nuclei left would be reduced by a factor of 2^6, which is equal to 64. Hence, the amount of nuclei left is 64 times less than at the start.

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.

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.

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.

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.

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.

Galvanization is a healing method that utilizes direct electrical current. It involves the application of a small, direct electric current to a specific area of the body, typically through the use of electrodes. This method is commonly used in physical therapy to reduce pain and inflammation, promote tissue healing, and improve blood circulation. The direct electrical current helps stimulate the nerves and muscles, resulting in pain relief and enhanced healing processes.

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.

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.

The Reynolds number is a dimensionless number that describes the nature of fluid flow, indicating whether the flow is laminar or turbulent. It is not related to the flow speed or vessel crosscut area, nor does it show the speed difference of ultrasound waves in fluid versus air. The Reynolds number is calculated using the ratio of average laminar fluid flow speed and maximum laminar fluid flow speed.

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.