physics 25/09/2023
What are base quantities?
Fundamental and independent properties of the world. Length, time & mass
What are derived quantities?
Something that can be measured, derived from the base quantities.
What are SI units?
International System of Units
What is currents measured in?
Ampere
What is temperature measured in?
Kelvin
What are the amount of atoms measured in?
Moles
What is luminosity measured in?
Candela
What does one mole equal?
6.022 × 10²³ units of that substance
What does one kilowatt (kW) equal?
1,000 Watts
What is the SI unit of speed?
Metres per second
What is energy measured in?
Joules
What is radioactivity measured in?
Becquerel
What is electric charge measured in?
Coulomb
What is electrical potential measured in?
Volts
What is frequency measured in?
Hertz
What is 1 million Watts equal to?
1 Megawatt
What are the common radiography prefixes?
Kilovolt, milliamp and millisievert
How is the intensity of an x-ray calculated?
mAs × kV
What are the number of x-rays directly dependent on?
The mAs, if you double the mAs you get twice as many x-rays
When should you change the mA as a radiographer?
When you want to prevent movement or have an image where the respiration blurs out the lungs
How is 1 mAs calculated?
1,000 mA × 0.001 seconds
What do you multiply together to get mAs?
mA × seconds
What do you divide together to calculate the number of seconds used?
mAs divided by mA
What do you divide together to calculate the mA?
mAs divided by the seconds
What is the mAs when you have 500 mA and 0.02 seconds?
10 mAs
What is the mA when you have 0.1 seconds and 25 mAs?
250 mA
What are the seconds when you have 400 mA and 8 mAs?
0.02 seconds