Essay on Study medical physics

Submitted By melissamackie
Words: 770
Pages: 4

Quantity: what is measured
Unit: how much is measured Fundamental quantities and units are defined standard
Derived units are combined fundamental quantities
Radation: Energy in transit → in the form of particles or waves →an initial excited state to a less excited state.
Particulate radiation: atomic or subatomic particles that carry energy as kinetic energy of mass in motion
Electromagnetic radiation: energy carried by electrical or magnetic waves travelling through space at the speed of light.
• Radio active decay emits both forms of radiation (particulate and electromagnetic
Process of Radiation:
1. Incident radiation
2. Interaction medium
3. Induced signal
4. Data Analysis

Electromagnetic radiation is used throughout our day to day lives (to microwave our food, treat cancer, to see etc). We can see as our eyes are able to detect visible light in the EM spectrum.

Light acts as a wave and also a particle
Defined as: Speed (v) = wavelength * frequency

Photons (particle light) has no mass and no electrical charge. Define as:
Energy (kEV)= 1.24/wavelength

EM SPECTRUM: Tranverse waves. Waves are distinguished by their wavelength and frequency. The more oscillations the higher the frequency; the higher the frequency the more energy (the shorter the wave length).

Our eyes can detect colour, as a wavelength of a certain frequency hits the retina at the back of our eye and sends a signal to the brain.

Building blocks:
Matter is made from elements
Elements are made from atoms
Atoms is the smallest amount of chemical to retain its prosperities
Atoms have a dense positively charged nucleus
Orbitals of electrons exist around atom
→similar to structure of solar system
Number of Neurtons: Z
Isotopes is an element of the same chemical properties, but a different number of neutrons.

Each electronic shell has a number of substrates
Pauli exclusion Principle: only a given number of electrons can exist on each subshell.
Electrons stay tightly bound to the nucleus.
Energy needed to remove electron from shell is called binding energy.
K needs the highest amount of energy to be removed from shell as it is the closest to the nucleus.

Electrons can temporality go to another shell by aborbing energy.
→unstable atom. An atom rearranges itself (deexcites) by emitting light (EM waves).
In light atoms the Auger effect takes place, where an electron’s spot in K or L will be taken/occupied by that of another in a higher shell (M). → Releases energy subsequently absorbed by an electron in the M, giving it enough energy to leave the atom.

Mass of electrons: A= Z + N (number of protons + number of neutrons)

Nucleus is smallest part of atom. Neucleons are big, but protons and neutrons attract (columbic force), making the nucleus dense → smaller than electrons.

Radioactive decay: gamma, alpha and beta →neucleur and repulsive force of protons are not balanced.

Radionucleuids: ground state of neuclus, most stable

Excited state: extremely unstable →short existence →decay

Metastable state: still unstable →longer life
• Stability of nuclide determined by strength of electromagnetic force

Isotopes: same number of protons
Isotones: same number of neutrons
Isobars: same mass number

206 bones in the body
• 80 axial skeleton
• 126 appendicular skeleton