CIE A Level Physics复习笔记25.2.1 Emission Spectra
Emission Spectra Astronomers are very limited in how they can investigate objects in the space All of the techniques used involve analysing the light emitted from the star, or galaxy One of these t...
CIE A Level Physics复习笔记25.1.4 Stefan-Boltzmann Law & Stellar Radii
Stefan-Boltzmann Law A star’s luminosity depends on two factors: Its surface temperature Its radius The relationship between these is known as the?Stefan-Boltzmann Law, which states: The total ener...
CIE A Level Physics复习笔记25.1.3 Wien's Displacement Law
Wien's Displacement Law Wien’s displacement law relates the observed wavelength of light from a star to its surface temperature, it states: The black body radiation curve for different temperatures...
CIE A Level Physics复习笔记25.1.2 Standard Candles & Stellar Distances
Standard Candles A standard candle is defined as: An astronomical object which has a known luminosity due to a characteristic quality possessed by that class of object Examples of standard candles ...
CIE A Level Physics复习笔记25.1.1 Luminosity & Radiant Flux
Defining Luminosity Luminosity?L?is defined as: The total power output of radiation emitted by a star It is measured in units of?Watts (W) Radiant flux intensity?F?is defined as: The observed amoun...
CIE A Level Physics复习笔记24.2.3 Detecting Gamma-Rays from PET Scanning
Detecting Gamma-Rays from PET Scanning The patient lays stationary in a tube surrounded by a ring of detectors Images of slices of the body can be taken to show the position of the?radioactive trac...
CIE A Level Physics复习笔记24.2.2 Annihilation in PET Scanning
The Process of Annihilation When a positron is emitted from a tracer in the body, it travels less than a millimetre before it collides with an electron The positron and the electron will?annihilate...
CIE A Level Physics复习笔记24.2.1 Radioactive Tracers
Radioactive Tracers A?radioactive tracer?is defined as: A radioactive substance that can be absorbed by tissue in order to study the structure and function of organs in the body Radioactive?isotope...
CIE A Level Physics复习笔记24.1.8 Computed Tomography Scanning
Computed Tomography Scanning A simple X-ray image can provide useful, but limited, information about internal structures in a 2D image When a more comprehensive image is needed, a?computerised axia...
