Physics Flashcards
Protons
Positive Charge, Define the element
Neutrons
Neutral charge, dictate isotopes
Electrons
Negative charge, dictate chemical reactivity
Matter
Anything with a mass and volume
What Is matter composed of?
Elements and compounds
Elements
Pure substances with one type of atom
Compounds
Chemically bonded elements fixed ratios
What are the two types of molecules?
Element molecules and compound molecules
Element molecules
Atoms of the same element
Compound molecules
Atoms of different elements
How is the periodic table organised
By atomic number and properties
Periodic table groups
Share similar properties due to valence electrons
Periodic table periods
Represent increasing atomic number and electron shells
Key trends in the periodic table
Electronegativity, ionisation energy, atomic radius
Valence electrons
Define chemical interactions
Electron excitation
Electrons absorb energy and move to higher levels, releasing photons upon return
Ionisation
Formation of ions by gaining or losing electrons
Potential energy
Energy stored due to position or state
Types of potential energy
Gravitational, chemical, elastic
Potential energy formula
PE = mgh
Kinetic energy
Energy of motion
Kinetic energy formula
KE = ½MV²
Heat transfers via
Conduction, convection and radiation
Specific heat capacity and thermal capacity
Describe how substances absorb heat
Electromagnetic Radiation Characteristic
Includes light and xrays
Defined by wavelength, frequency, and amplitude
EMR travels at a constant speed
Electromagnetic Radiation Properties
Inverse Square law: intensity decreases with the square of distance.
Gamma rays are used in medicine
Ground state
The ground state is the most stable configuration of an atom, where electrons occupy the lowest available energy levels
Electrons fill starting with the lowest energy levels
Energy Absorption
Energy can be absorbed from heat, light, and electricity
A photon must have equal energy to the energy gap between two levels
Energy Absorption Formula
E=hv
Transition to excited state
Energy absorption allows the electronic to overcome the energy balance
The electron shifts to a state further from the nucleus
The excited state is unstable, and the electron typically returns to the ground state
Excited State Characteristics
Unstable the electron remains in this state
Multiple levels if sufficient energy is absorbed
Excited State Implications
Excited atoms may participate in specific reactions
Return to ground state energy release
When the electron drops back to a lower energy level, it releases absorbed energy
Return to ground state emission spectrum
The emitted photons have specific energy corresponding to spectral lines
This forms the basis for spectroscopy
Uses for electron excitation
Spectroscopy, fluorescene, photochemistry, lasers
X-Ray tube components
Glass/Metal enclosure
Cathode
Anode
Vacuum
Induction Motor
Glass/Metal Enclosure
Maintains vacuum, dissipates heat
Cathode
Negative end, produces electrons via thermionic emission
Anode
Positive end, the target where x-rays are produces
Vacuum
Ensures unimpeded electron flow and prevents oxidation
Induction Motor
Rotates the anode for heat distribution
X-ray tube materials
Tungsten, Metal tubes
Tungsten
High melting point, excellent for filaments and anodes targets
Metal Tubes
More durable, better heat management, reduced arching
Anode Types
Stationary, Rotating
Stationary Anode
Older designs, limited heat capacity
Rotating Anode
Modern design, spreads heats, supports higher energy techniques
Cooling Techniques
Conduction, Convection, Radiation
Assisted by oil, fans and heat exchange
Electron Emission Processes
Thermionic Emission, Space Charge Effect
Thermionic Emission
Heated tungsten filament emits electrons, Thorium added to reduce melting risk
Space Charge Effect
Excess electron cloud limits further emission, managed by increasing anode voltage
Electron Excitements
High speed electrons collide with tungsten anode, producing x-rays and heat
Tube Housing Protection
Electrical: Mineral oil
Thermal: Oil dissipates heat
Radiation: Lead lining
Tube Housing designs
Hooded anodes
Hooded Anodes
Reduces undesired x-ray emissions
Improves beam focus
Hooded Anodes Purposes
Radiation Shielding, Beam focus and quality
Hooded Anodes Features
Anodes Structure, Large Filament, Window Placement
X-Ray Properties Characteristics
No mass, no electrical charge, unaffected by electric or magnetic fields, travels in straight lines
X-Ray Production Mechanisms
Bremsstrahlung Radiation, Characteristic Radiation
X-Ray Generation Key Processes
Filament Heating, Electron Acceleration, Collision with the anode
Bremsstrahlung Radiation Features
Produces a range of photon energies, higher beam X-rays have shorter wavelengths
