1 - Working As A Physicist Flashcards
What’s the basic units of mass
Kilogram (kg)
What’s the basic units of time
Second (s)
What’s the unit of length
Metre (m)
What’s the unit of electric current
Ampere (A)
What’s the unit of temperature
Kelvin (K)
What’s the units for an amount of substance
Mole (mol)
What’s the unit for luminous intensity
Candela (cd)
What are SI units
Standard units - there are meetings that make definitions for basic quantity’s and units
What is the definition of a kilogram
The kilogram is a unit of mass and it’s equal to the mass of the international prototype of the kilogram
What’s the defitnion of the second
The second is the duration of 9192631770 periods of the radiation corresponding to the transition between the 2 hyperfine levels of the ground state of the caesium- 133 atom
Define the metre
The length of the path travelled by light in vacuum during a time interval of 1/299792458 of a second
Define the ampere
The ampere is that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross - section, and placed 1m apart in vacuum, would produce between these conductors a force
Equal to 2 x 10^-7 Newton per metre of length
Define kelvin
The kelvin, unit of thermodynamic temperature, is the fraction of 1/273.16 of the thermodynamic temperature of the triple point of water
What is a base unit
Fundamental qualities of things in the universe - eg the length of a pencil is a base unit
Length is a base unit
What’s a derived unit
Eg speed - when you have to consider other factors to get that unit
We can just list base units that went together in deriving the derived quantity - eg speed is measured in m s^-1
Some derived units (eg force) should be kg m s ^-2 but we use newton (N)
What type of unit are SI units?
Base units
Define a mole as a unit
A mole is the amount of substance of a system which contains as many elementary entities as there are atoms in 0.012kg of carbon-12 (when the mole is used, the elementary entities must be specified and may be atoms, molecules, ions, electrons, other particles or specified groups of such particles)
Define the candela as a unit
The candela is the luminous intensity, in a given directjon, of a source that emits monochromatic radiation of frequency 540 x 10^12 hertz and that has a radiant intensity in that direction of 1/683 watt per steradian
What’s the unit of the derived quantity = force?
Newton (N)
What’s the unit of the derived quantity = Energy (work)
Joule (J)
What the unit for the derived quantity : power
Watt (W)
What’s the unit for the derived quantity : frequency
Hertz (Hz)
What’s the unit of the derived quantity : charge
Coulomb (C)
What’s the unit for the derived quantity : voltage
Volt (V)
