How many electrons correspond to 1 coulomb?
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1 coulomb is equivalent to 6.24 × 10^18 electrons.
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How many electrons correspond to 1 coulomb?
1 coulomb is equivalent to 6.24 × 10^18 electrons.
What is the common gas outlet pressure for medical gases?
2 cm H2O.
What is the formula for force?
Force = mass × acceleration (F = ma).
What is 1 Hertz (Hz)?
1 cycle per second.
What is kinetic energy?
The energy a body possesses because of its motion.
What is absolute zero?
The lowest possible temperature where nothing could be colder and all thermal motion stops, precisely 0 K or -273.15 °C.
What is the cylinder pressure for oxygen and air?
137 bar.
What is an under-damped system?
An under-damped system changes quickly in response to input, overshooting and oscillating around the true value before settling.
What is critical temperature (CT)?
The temperature above which a gas cannot be liquefied by pressure alone.
What is the abbreviation for the International System of Units?
SI units.
What is the natural frequency of the transducer kit typically designed to be?
Around 45,000 Hz.
What is the damping factor 'D' in a critically damped system?
In a critically damped system, D = 1.
What happens to the gauge pressure of a nitrous oxide cylinder over time when used continuously?
Initially, the gauge pressure remains constant until all the liquid is used up, after which it declines over time following Boyle's law.
How many base units are there in the SI system?
Seven base units.
What is the role of the input in a measurement system?
It is the parameter chosen to be measured, e.g., blood pressure (BP).
How can you calculate the volume of N2O that can be discharged from a cylinder?
Weigh the cylinder to find the weight of remaining N2O, then apply Avogadro’s hypothesis: Volume of N2O (L) = (Cylinder weight - Tare weight) / Molecular weight of N2O × 22.4 L.
What is hysteresis in a measurement system?
Hysteresis occurs when the output of the system alters depending on whether the input is rising or falling.
What forces are balanced in a single-stage pressure regulator?
The force from the spring against the force generated by pressure against the diaphragm.
What are the components of a standard measurement system?
Input, Transducer, Transmission path, Conditioning unit, Display unit, Output.
What effect does increasing the length of the saline column have on damping?
It increases damping but decreases the system's natural frequency significantly.
What does damping describe in a measurement system?
Damping describes the resistance of a system to oscillation resulting from a change in the input.
What does a transducer do?
It converts one form of energy into another, e.g., a strain gauge in blood pressure monitoring.
When did the creation of the decimal metric system begin?
During the eighteenth-century French revolution.
What is the equation relating pressure and volume for a gas at constant temperature?
P1 × v1 = P2 × v2.
What defines an over-damped system?
An over-damped system has damping greater than critical, potentially changing so slowly that it never reaches the true value.
What is the definition of a gas?
A substance that is above its critical temperature and will expand to fill any available space.
Is blood pressure considered absolute or gauge pressure?
Blood pressure is a gauge pressure.
What is the critical temperature of nitrous oxide?
36.5 °C.
What is the base unit for mass in the SI system?
Kilogram (kg).
What causes inaccuracies in manometer readings?
Surface tension can lead to over-readings in water manometers and under-readings in mercury manometers.
How does the second-stage chamber in a two-stage pressure regulator operate?
It contains a larger diaphragm that operates a valve connecting it to the first-stage low-pressure chamber.
What is the mathematical expression of Boyle's law?
PV = Constant or P ∝ 1/V.
What is resonance in a measurement system?
Resonance is the tendency of a system to oscillate at maximum amplitude at certain frequencies, determined by the mass and stiffness of the system.
What is a potential problem with a system that rises quickly?
It may overshoot in its reading.
What is the filling ratio of nitrous oxide cylinders in temperate climates?
0.75.
What is the prefix for 10² in SI units?
Hecto (h).
How is the ideal gas law used in cryotherapy?
It explains how a sudden expansion of gas through a probe results in a very cold tip, used to freeze lesions.
What is the definition of a volt (V)?
The potential difference between two points of a conducting wire when 1 joule of work is done to move 1 coulomb of charge between them.
What is the storage capacity of a typical VIE?
Up to 1500 liters of liquid oxygen.
How is 1 newton defined?
The force required to accelerate a 1 kg mass at a rate of 1 m/s².
What is the difference between partial and total pressures?
Partial pressure is the pressure exerted by an individual gas, while total pressure is the sum of all partial pressures in a mixture.
What are the two chambers in a single-stage pressure regulator?
A high-pressure chamber and a low or control pressure chamber.
What is gauge pressure?
Pressure measurements above or below atmospheric pressure; an empty cylinder has a gauge pressure of zero.
How can the Ideal Gas Equation be used?
It allows conversion between different sets of conditions for a given mass of gas.
How is nitrous oxide (N2O) manufactured?
By the thermal decomposition of ammonium nitrate.
What is the derived unit for density?
Kilogram per cubic metre (kg/m³).
How do manometers work?
They consist of a fluid-filled column open to the atmosphere, measuring gauge pressure based on fluid height, density, and gravitational force.
What is an example of a two-stage pressure regulator?
A demand valve on an entonox cylinder or diving cylinder.
What are the two supplementary units that were abolished in 1995?
Plane angle (radian) and solid angle (steradian).
How can noise be overcome in measurement systems?
Noise can be reduced by adding filters, such as high pass, low pass, and notch filters, or by averaging out repetitive signals.
What happens when a patient inspires using a two-stage pressure regulator?
The pressure within the second-stage chamber reduces, moving the diaphragm and opening the valve to allow gas to enter.
How does a Bourdon gauge function?
It consists of a coiled metal tube that changes shape under pressure, moving a pointer across a scale.
What do oxygen concentrators use to deliver oxygen?
Zeolite adsorbents.
What is the pseudocritical temperature for entonox?
-5.5 °C.
What happens to a liquid when its temperature is lowered below its freezing point?
It turns into a solid.
At what temperature is liquid oxygen stored in a VIE?
Between −150 and −170 °C.
What does Charles's Law state?
At constant pressure, the volume of a given mass of gas is directly proportional to the absolute temperature.
What is the Ideal Gas Equation?
PV = nRT, where P is pressure, V is volume, n is the number of moles, R is the universal gas constant, and T is temperature.
What is absolute humidity?
The mass of water vapor present in a particular sample of air at a given temperature, measured as kg m–3.
What is absolute pressure?
Pressure measurements that include atmospheric pressure; it is gauge pressure plus atmospheric pressure.
What effect does an increase in inlet pressure have on the diaphragm in a single-stage regulator?
The diaphragm will lift, causing the conical valve to shut.
What is the base unit for length in the SI system?
Metre (m).
When should calibration be performed?
Calibration should be performed after a predetermined time, after a set number of uses, when unexpected results occur, or if the machine is moved or damaged.
At what pressure is nitrous oxide stored in cylinders?
52 bar.
What does Boyle's law state?
At constant temperature, the absolute pressure of a given mass of gas is inversely proportional to its volume.
What is the filling ratio of nitrous oxide cylinders in tropical countries?
0.67.
What is the difference between analogue and digital measurement systems?
Analogue systems have continuous output signals, while digital systems have discontinuous output signals.
What is the cylinder color for nitrous oxide?
Blue/Blue.
What happens when energy is added to a system at the right moment?
Adding energy at the right moment increases the amplitude of oscillations, which can interfere with the output reading.
What is the SI unit of mass?
Kilogram.
What is the prefix for 10⁶ in SI units?
Mega (M).
How is force defined in physics?
Force is a vector quantity that can cause an object with mass to accelerate, defined by Newton's second law as mass multiplied by acceleration.
What is the derived SI unit of force?
The newton (N).
What does Dalton's law state about partial pressures?
In a gas mixture, the pressure exerted by each gas is equal to the pressure it would exert if it occupied the container alone.
What is the SI unit of heat capacity?
Joule per kelvin.
What is the absolute pressure of a cylinder with a gauge pressure of 13,700 kPa?
13,800 kPa (gauge pressure + atmospheric pressure).
What is relative humidity?
The mass of water in a given volume of air, expressed as a percentage of the maximum mass of water that the air could hold at the given temperature.
What is resistance in electrical terms?
The property of a conductor to oppose the flow of current through it, with the derived SI unit being the Ohm (Ω).
What is the relationship described by Gay-Lussac's Law?
At constant volume, the absolute pressure of a given mass of gas varies directly with the absolute temperature.
What does Avogadro’s hypothesis state?
At standard temperature and pressure, 1 mole of gas occupies 22.4 L.
What is the critical temperature for O2?
−119 °C.
What is the derived unit for volume?
Cubic metre (m³).
What is the significance of the Ideal Gas Equation?
It unites Charles's Law, Gay-Lussac's Law, and other gas laws under one equation.
What are the characteristics of ideal invasive BP monitoring equipment?
It should have a short, stiff, wide cannula, no connections, and no air bubbles to maintain high natural frequency.
What is the derived unit for velocity?
Metre per second (m/s).
What causes damping in a system?
Damping is the result of frictional forces working in that system.
What is the SI unit of time?
Second (s), defined by the frequency of radiation emitted by caesium-133 in its ground state.
What are derived units?
Units formed by combination of various base units according to mathematical relationships.
How does a mercury barometer work?
It has a Torricellian vacuum above mercury, measuring pressure based on the height of the mercury column.
What is Dalton’s law of partial pressures?
It states that the total pressure exerted by a gaseous mixture is equal to the sum of the partial pressures of each individual gas.
What does accuracy in a measurement system refer to?
How closely the output reflects the true value being measured.
What is the critical temperature?
The temperature above which a gas cannot be liquefied by pressure alone.
What is drift in a measurement system?
It is the movement of the output away from the true input value, usually caused by changing properties of the equipment.
Why is the gas cylinder on an anaesthetic machine not connected directly to the rotameter block?
To prevent variable flow of gas or vapour to the patient due to high pressures and surges.
What is the prefix for 10¹² in SI units?
Tera (T).
What is the relationship between syringe size and pressure when dislodging a blockage?
A 2 mL syringe generates higher pressure due to its smaller cross-sectional area, making it more effective for dislodging blockages.
What is the definition of Pascal (Pa)?
1 Pa is the force of 1 N acting over 1 m².
What is latent heat?
The energy released or absorbed by a substance when it changes phase at a given temperature.
What is the natural frequency of the arterial pulse?
Around 20 Hz.
How does attaching a long column of saline affect the natural frequency of the measuring system?
It reduces the natural frequency from 45,000 Hz to around 15 Hz.
What phenomenon occurs when the frequency of the measuring system is close to that of the input?
Under-damping, leading to falsely elevated and depressed peaks and troughs in the output display.
What is calibration?
Calibration is a process in which the output of a measuring device is compared to a standard of known units of measure to determine its accuracy.
What is Avogadro’s hypothesis?
It states that equal volumes of gases at a given temperature and pressure contain the same numbers of molecules.
What conditions define standard temperature and pressure (STP)?
273.15 K and 101.3 kPa.
Why is the Poynting effect important for entonox cylinders?
Because if the temperature falls below -5.5 °C, a liquid mixture can form, affecting the gas mixture delivered to patients.
What is saturated vapour pressure (SVP)?
The pressure exerted by a vapour in contact with and in equilibrium with its liquid phase within a closed system at a given temperature.
What is the function of the transmission path in a measurement system?
It carries the electrical signal to the conditioning unit.
How can the risks associated with the Poynting effect be minimized for entonox cylinders?
By storing them horizontally at temperatures above 5 °C.
What are pressure regulators?
Devices that reduce a higher variable inlet pressure to a constant lower outlet pressure.
Why do different textbooks quote varying gauge pressures for N2O cylinders?
Because gauge pressures reflect the saturation vapor pressure of N2O above its liquid, which varies with temperature.
What is a coulomb?
The unit of charge, defined as the amount of charge passing a given point per second when 1 A of current is flowing.
What purity level does the fractional distillation method achieve for oxygen?
Over 99% pure.
What state is carbon dioxide in at room temperature?
Vapour.
What is the freezing point?
The temperature at which the liquid and solid phases of a substance are in equilibrium at a given pressure.
What devices are used to ensure safe and constant gas mixtures during anaesthesia?
Pressure regulators, flow restrictors, and pressure relief valves.
How does gravity affect the weight equivalent of one newton?
One newton is equivalent to a 102 g weight due to gravity's acceleration of 9.81 m/s².
What does 1 Ohm (Ω) represent?
The resistance between two points of a conductor when a constant potential difference of 1 volt applied between them produces a current of 1 ampere.
How does altitude affect partial pressures of gases?
Partial pressures of gases, including oxygen, fall with increasing altitude.
What two standards were placed in the Archives de la République in Paris?
The metre and kilogram.
What is the symbol for area in SI units?
m² (square metre).
What causes damping in the measurement system?
Friction in the measurement system.
Why is the lung compliance curve an example of hysteresis?
Because it exhibits hysteresis due to the elastic energy stored within it.
What is the definition of vapor?
A gas that is below its critical temperature.
What is the practical consequence of an under-damped system in arterial pressure monitoring?
Inappropriately over-represented arterial pressure readings.
How is Avogadro’s hypothesis applied in calculating the contents of an N2O cylinder?
By using the formula: No. of moles of N2O = (Cylinder weight - Tare weight) / Molecular weight of N2O.
What is pseudocritical temperature?
The temperature at which a mixture of gases may separate into individual constituents.
What is a calorie?
The amount of energy required to increase the temperature of 1 g of water by 1 °C, equivalent to 4.16 J.
How do you calculate the volume of O2 available from an O2 cylinder?
Using the ideal gas law and the absolute pressure of the cylinder.
What is a direct pressure regulator?
A regulator where the cylinder pressure opens the valve.
What is the named derived unit for energy?
Joule (J).
What is the latent heat of vaporization?
The amount of heat required to convert a unit mass of a liquid at its boiling point into vapor without an increase in temperature.
What is the prefix for 10⁻³ in SI units?
Milli (m).
What is the SI unit of pressure?
Pascal (N/m²).
What is the derived SI unit of power?
Watt (W), defined as 1 joule per second.
How is momentum calculated?
Momentum is calculated as mass multiplied by velocity.
What is the pressure of the oxygen delivered to hospitals from cylinder manifolds?
4 bar (400 kPa).
What is potential energy?
The energy of a body or system as a result of its position in an electric, magnetic, or gravitational field.
What is a joule (J)?
The work done when applying a force of 1 newton through a distance of 1 meter.
What characterizes a critically damped system?
A critically damped system has a longer response time than an under-damped system, with no significant overshoot and minimal oscillations.
What does the variable 'R' represent in the Ideal Gas Equation?
The universal gas constant, which is approximately 8.32144 J/(K·mol).
How does a system without hysteresis behave?
In a system without hysteresis, the output can be predicted from the input alone.
What is an optimally damped system?
An optimally damped system accepts some oscillations and overshoot to achieve a faster response time, with 64% of energy removed (D = 0.64).
What is the SI unit of electric current?
Ampere (A), which is the current that produces a force of 2 × 10–7 newtons per meter between two parallel wires in a vacuum.
What is the cylinder pressure for nitrous oxide at room temperature?
52 bar.
What is critical temperature?
The temperature above which a substance cannot be liquefied, regardless of the pressure applied.
What is the derived unit for acceleration?
Metre per second squared (m/s²).
What are barometers used for?
Barometers measure absolute pressure and are closed to the atmosphere.
What is specific heat capacity (SHC)?
The amount of energy required to raise the temperature of 1 kg of a substance by 1 °C.
What is the base unit for time in the SI system?
Second (s).
What is the latent heat of fusion?
The amount of heat required to convert a unit mass of a solid at its melting point into a liquid without an increase in temperature.
What issue can arise from a system that rises too slowly?
It may never reach the new elevated input value or take too long to be useful.
What is a two-stage pressure regulator?
A regulator where the output of one stage is the input of another, reducing wear and pressure fluctuations.
How does mass differ from weight?
Unlike weight, mass does not alter under conditions of differing gravity.
What is the prefix for 10⁻⁶ in SI units?
Micro (μ).
What is a mole in terms of substance amount?
A quantity containing the same number of particles as there are atoms in 12 g of carbon-12, which is 6.022 × 10^23 (Avogadro's constant).
How is the remaining amount of oxygen in a VIE measured?
By weighing the storage vessel.
What does pH measure?
The negative logarithm to the base 10 of the hydrogen ion concentration in a solution.
How is power defined?
The rate of doing work, with the unit of power being the watt (1 watt = 1 joule per second).
What is the SI unit of temperature?
Kelvin (K).
What is a gas?
A substance that exists above its critical temperature.
How is the orifice of the conical valve in a single-stage regulator controlled?
By a spring connected to a diaphragm in the control chamber.
How much oxygen (O2) is available in a cylinder if 10 L remains in it?
1370 L of O2 is available.
What is an 'ideal gas'?
A theoretical gas where molecules behave as individual particles moving randomly, independent of each other.
What is the Poynting effect?
It refers to the liquefaction and separation of individual gas components in a mixture when exposed to temperatures below its pseudocritical temperature.
What is the role of the spring in a single-stage pressure regulator?
It can fix or vary the pressure in the control chamber by altering its tension.
Why should there be no air bubbles in the BP monitoring system?
Air bubbles are compressible and decrease energy transmission, resulting in a damped trace.
What happens to entonox cylinders during mountain rescues if the temperature drops below -5.5 °C?
A liquid mixture containing mostly N2O with about 20% O2 can form, leading to a hypoxic gas mixture being delivered to patients.
What is the ideal gas law equation?
P1V1/T1 = P2V2/T2.
What happens in the conditioning unit of a measurement system?
The electrical signal is processed, analyzed, and passed to the display unit.
What is the SI unit of luminous intensity?
Candela (cd), defined as the luminous intensity of a source emitting monochromatic radiation of frequency 540 × 10^12 hertz.
How does mass and stiffness affect oscillation in a system?
Greater mass results in slower oscillations, while greater stiffness leads to faster oscillations.
What is the specific latent heat of vaporisation?
The amount of heat required to convert a unit mass of a liquid at its boiling point into a gas without an increase in temperature, at a given pressure.
What happens to gas temperature during rapid compression or expansion?
Rapid compression raises the temperature, while sudden expansion lowers it.
What is a slave pressure regulator?
A regulator where the output of one valve is dependent on the output of another.
What is the main hospital supply of oxygen stored in?
A vacuum-insulated evaporator (VIE).
What is the SI unit of force?
Newton (N).
What is the definition of a Newton (N)?
1 N is the force required to accelerate a mass of 1 kg by 1 m per second squared.
What is heat capacity?
The amount of heat required to raise the temperature of an object by 1 °C.
Why should calibration be performed with at least two standards?
Using at least two standards increases the accuracy of the resultant measuring device.
What is Avogadro’s number?
6.022 × 10^23 particles, which is the number of particles in one mole of a substance.
What are the gas laws?
A set of rules governing the relationship between thermodynamic temperature, volume, and pressure of ideal gases.
What is signal noise?
Signal noise describes unwanted external information that alters the output of a transducer.
Define pressure.
Force per unit area; the SI unit is the pascal (N/m²).
What is the critical temperature for oxygen?
-119 °C.
What are aneroid gauges used for?
They measure high pressures where manometers would be impractical.
What is Henry’s law?
It states that the amount of gas dissolved in a liquid is proportional to its partial pressure above that liquid at a given temperature.
What is sensitivity in the context of measurement systems?
It determines how small a change in input will result in a change in output.
What is a vapour?
A substance in the gas phase below its critical temperature.
What is the SI unit of length?
Metre (m).
What is force?
That which changes a body’s state of rest or motion.
What type of cylinders are used for oxygen on anaesthetic machines?
Molybdenum steel cylinders (size E cylinders).
What is the boiling point?
The temperature at which the vapor pressure of a liquid equals the surrounding ambient pressure, causing the liquid to change into vapor.
What is 'response time' in a measurement system?
Response time is the time taken for the output to reach 90% of its final reading.
What is critical pressure?
The pressure required to liquefy a gas at its critical temperature.
What is the expression for pressure in terms of SI units?
N/m² (newton per square metre).
What is the most common method of manufacturing oxygen commercially?
Fractional distillation of liquefied air.
What is an indirect pressure regulator?
A regulator where a spring opens the valve in response to falling outlet pressure.
What is the triple point of water?
The temperature and pressure at which water exists in equilibrium as liquid, solid, and vapour; temperature = 0.01 °C or 273.16 K, pressure = 0.006 atm or 611.73 pascals.
What is the purity level of oxygen delivered by oxygen concentrators?
90–93% pure.
What is the cylinder color for heliox?
Brown/Brown & White.
What is weight?
The gravitational force acting on an object, measured in newtons; weight = mass in kg × gravitational acceleration (9.81 m/s²).
Is atmospheric pressure constant?
No, atmospheric pressure varies with altitude and temperature.
What is pressure?
Force per unit area, with the derived SI unit being the Pascal (Pa).
Why are nitrous oxide cylinders only partially filled?
Because liquids are less compressible than gases, preventing explosions at high temperatures.
What is the named derived unit for force?
Newton (N).
What is 'rise time' in a measurement system?
Rise time is the time taken for the output to rise from 10 to 90% of its final reading.
What is the specific heat capacity of water?
4.16 kJ/kg °C.
What is the base unit for temperature in the SI system?
Kelvin (K).
What is the cylinder pressure for air?
137 bar.
What is the definition of pressure?
Pressure is the force applied per unit area.
What does gain refer to in a measurement system?
The degree of amplification of the measurement system, or the output to input ratio.
How is the metre defined since 1983?
As the length of the path travelled by light in vacuum during the time interval of 1/299,792,458 of a second.
What pressure is liquid oxygen stored at in a VIE?
7 bar.
What is a gas?
One of the four fundamental states of matter, distinguished by vast separation between individual particles.
What law is used to calculate the volume of oxygen available from a cylinder?
The ideal gas law.
What is 1 Kelvin equal to?
1/273.16 of the thermodynamic scale temperature of the triple point of water.
Why are oxygen cylinders filled to 137 bar?
Because cylinder technology originally measured filling pressures in psi, equivalent to 2000 psi.