Physics & Equipment Flashcards
Accuracy
The ability of a measurement device to match the actual value being measured
Precision
The reproducibility of repeated measurements and a measure of their likely spread
Drift
A fixed deviation from the true value at all points in the measured range. Drift can be corrected by zeroing
Hysteresis
Measurement varies depending on whether or not the input variable is increasing or decreasing
Non-linearity
Absence of a true linear relationship between input value and measured value
Calibration
Checks for linearity by measuring 2 or more points and ascribing a relationship between them. The more points on the line, the more one can be certain of a linear relationship.
The 7 Base SI Units
- Second (Time)
- Mole (Amount)
- Meter (Distance)
- Ampere (Current)
- Candela (Luminosity)
- Kelvin (Temperature)
- Kilogram (Mass)
Define second
The duration of a given number of oscillations of the caesium-133 atom
Define metre
The metre is the length of the path travelled by light in vacuum during a time interval of a fraction of a second
Define mole
The amount of substance which contrains as many elementary particles as there are atoms in 0.012kg of carbon-12
Define Ampere
The current in two parallel infinately long conductors placed 1 metre apart in a vacuum such that the force between them is 2 x 10-7 N.m-1
Define candela
The candela is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540×10^12 hertz and that has a radiant intensity in that direction of 1/683 watt per steradian.
Define kilogram
The units for mass. Defined as the mass of the international prototype Kg held in France, Sèvres
Define Kelvin
1/273.16 of the thermodynamic temperature of the triple point of water
Newton
A derived SI unit describing force. It’s units are Kg.m.s-2
Pressure
A derived SI unit that describes force applied over a given area, such that it has the units N.m-2 or Pa.
mmHg
An imperial measure of pressure described by the change in height of a column of mercury by a driving pressure, such that 760mmHg=101KPa
Pascal
A derived SI unit of pressure such that atmospheric pressure is given as 101KPa
Joule
A derived SI unit of energy such that 1 joule = Nm = Kg.m2.s-2
Volt
A derived SI unit of electrical potential. One volt is defined as the difference in electric potential between two points of a conducting wire when an electric current of one ampere dissipates one watt of power between those points.
Watt
A measure of power. The amount of energy used per unit time. It’s units are J/s = Kg.m2.s-3
Ohm
The ohm is defined as a resistance between two points of a conductor when a constant potential difference of 1.0 volt, applied to these points, produces in the conductor a current of 1.0 ampere, the conductor not being the seat of any electromotive force.
Hertz
A measure of frequency. The number of oscillations in 1 second such that its units are s-1
Coloumb
A derived SI unit. It is the measure of charge, an intrinsic property of matter. 1 coulomb is defined as 1A.s and is also the charge carried by 6.24x10^18 electrons.
Kinetic energy
E=½mv2. The mechanical energy that a body has by virtue of its motion
Potential energy
The mechanical energy that a body has by virtue of its position; stored energy.
E=mgh
Force
A physical quantity that describes an interaction that can change the velocity of a mass such that F=ma. It has the units Newtons.
Momentum
A derived SI physical quantity defined as the product of a body’s mass and velocity with units Kg.m.s^-1
A hydrogen ion
A proton
pH
The negative log to base 10 of the concentration of hydrogen ions
Critical temperature
The temperature of an ideal gas at which no matter how much pressure is applied cannot be forced into its liquid state
Critical pressure
The pressure required to convert an ideal gas into its liquid state at its critical temperature
Filling Ratio
The ratio of the weight of a cylinder when partially filled with a liquid and it’s vapour (most commonly nitrous oxide) to the weight of the cylinder when completely filled with water
Weber
The derived SI unit of magnetic flux. It carries the base units kg.m2.s-2.A-1
Tesla
The derived SI unit of magnetic flux density. It carries the units Wb.m-2
Gauss
A deprecated unit of magnetic flux
1 Tesla = 105 Gauss
Describe 1 ATM in other units
- 1 Atmosphere
- 1.013 bar
- 101.325 kPa
- 14.696 PSI
- 760 mmHg
What is a LASER?
Laser stands for: Light Amplification by Stimulated Emission of Radiation. Lasers produce a coherent, collimated and monochromatic beam of light.
What are the wavelengths, colour and tissue penetration for Argon, CO2 and Nd:YAG lasers?
- Argon: 488-515nm, blue-green, 2mm
- CO2: 10600nm, far IR, 1mm
- Nd:YAG: 532, green, 3-5mm
Laser safety classes
- Power not to exceed max exposure to eye
- Visible laser beam only, <1mW, blind reflex 0.25s
- -
- Direct viewing extremely hazardous
What is the hagen-poiseuille equation?
Equation to describe laminar flow
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When is turbulent flow predicted?
Reynolds > 2000
What is the critical temperature of oxygen?
-119°C
What pressure is generated in VIEs if no oxygen is drawn off?
approx 700-1000 kPa. The SVP of oxygen at this temperature.
The minimum number of theatre air changes per hour.
20/hour
At what temperature is a VIE maintained?
- 160 degrees
How much O2 and N2O can a size E cylinder contain?
O2 - 680L
N2O - 1800L
What is a Bodok seal?
A Bonded Disk seal - prevents gas leakage at cylinder connection sites
At what pressure does the O2 failure alarm activate?
When supply pressure drops below 2 bar. At this point, an air entrainment valve is also opened to prevent a hypoxic mix
How much O2 does the oxygen flush deliver?
35-75 L/min directly from upstream to the vaporisers. Depending on how much flow is diverted through the flowmeters.
What is the accuracy of a flowmeter
+/- 2.5%
What are the pin indexes for O2, N2O, Air and CO2?
O2 - 5,2
N20 - 5,3
Air - 5,1
CO2 - 6,1