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.
