physics revision part 1
what is length measured in?
metres
what is mass measured in?
kilogram
what is time measured in?
seconds
what is current measured in?
ampere
what is temperature measured in?
kelvin
what is amount of substance measured in?
mole
what is luminosity measured in?
candela
what is zero degrees Kelvin in Celsius?
-273 Celsius
what does 1 mole equal?
number of atoms in 12g of carbon-12
what is avogadro's number?
6.022 x 10 to the power of 23
what is the SI unit of speed?
metres per second
what is the SI unit of density?
kg m-3
what is the ability to do work?
energy joule (J) (kg m-2 s-2)
how does magnetic flux density apply to radiography?
important in field strength in MRI
what is absorbed radiation dose measured in?
gray (gy)
what is the rate of doing work?
power (W) (joules per second)
what is radioactivity measured in?
becquerel
what is the definition of electric charge?
1C = 1A x 1s
how does electrical potential apply to radiography?
potential difference across an x-ray tube, acceleration of electrons and quality of x-ray beam
what is frequency measured in?
hertz / Hz
what is 1 million watts equal to?
1 megawatt / 1 MW
what is kV?
kilovolt
what is mA?
milliamp
what is mSv?
millisievert
what is the intensity of the x-ray beam determined by?
mAs x kV
what is the number of x-rays produced directly dependent on?
the mAs
when would it be necessary to change the mA or the time?
to prevent movement or have an image where the respiration blurs out the lungs