1. Electrostatics
1.1. Terminology
1.1.1. Electro Statics
1.1.1.1. the study of static electricity
1.1.1.2. the study of charges at rest
1.1.2. Polarisation
1.1.2.1. the partial or complete polar separation of positive and negative charge in a system
1.1.3. Quantisation
1.1.3.1. division of charge in smaller units
1.1.4. Conservation of Charge
1.1.4.1. the nett charge of an isolated system stays constant during any physical process
1.1.5. Quantisation of Charge
1.1.5.1. all electrical charge is an integer multiple of the elementary charge (1,6 x 10^-19)
1.1.6. Tribe-Electric Charge
1.1.6.1. process by which electrons are transferred, when 2 objects come into contact with each other and are now separated from each other
1.1.7. Dipoles
1.1.7.1. pair of opposite charges that are separated
1.2. Equations
1.2.1. nett charge
1.2.1.1. Q = nqe
1.2.2. after separation
1.2.2.1. Q1 + Q2 / 2
1.3. Types of Charges
1.3.1. all materials contain positive charges (photons) and negative charges (electrons)
1.3.2. protons and neutrons can’t be removed and are found in the orbitals
1.3.3. neutral object have the same amount of protons and electrons
1.3.4. (+) charged objects have lost electrons or have excess protons
1.3.5. (-) charged particles have lost protons or have excess electrons
1.4. Methods that Neutral Objects can Become Charged
1.4.1. Friction
1.4.1.1. when 2 objects / different materials are rubbed against each other or make contact, electrons are transferred form one object
1.4.1.2. one object looses electrons and the other gains them
1.4.1.3. also known as tribo-electric charge
1.4.2. Contact
1.4.2.1. when a charged conductor touches an identical neutral conductor, electrons are transferred to make the charge on the conductors equal
1.4.2.2. (+) conductor touches a neutral conductor = (-) charges are transferred form neutral to positive charge
1.4.3. Induction
1.4.3.1. a method of charging whereby the object ps do not touch one another
1.4.3.2. neutral electroscope is charged by induction
1.5. Polarisation
1.5.1. Examples
1.5.1.1. Charged balloon against a wall
1.5.1.1.1. the balloon’s (-) charge pushes the electrons in the molecules of the wall and leaves the excess positive charge on the surface
1.5.1.1.2. unlike charges attract
1.5.1.2. Charged balloon near paper
1.5.1.2.1. the (-) charged balloon repels the electrons in the paper
1.5.1.2.2. the charge inside the paper molecules are separated and leaves an excess (+) charge on the side when the balloon is
1.5.1.2.3. unlike charges attract
1.5.1.3. Charged balloon near water
1.5.1.3.1. water molecules direct themselves with the side that has the opposite charge (+) to the balloon and therefore the balloon attracts the water
1.5.1.3.2. unlike charged attract
1.5.2. Insulators
1.5.2.1. temporary dipoles are created
1.5.2.1.1. instantaneous dipoles formed in non-polar molecules during induce polarisation
1.5.2.2. unlike conductors, electrons are bonded to the atoms of insulators and cannot move freely through the substance
1.5.2.3. a charged object can exercise electrostatic power in a neutral insulator through polarisation
1.5.3. Water
1.5.3.1. some substance a (water) consist of molecules that are already polarised under normal circumstances
1.5.3.2. water consist of 2 hydrogen atoms and 1 oxygen atom
1.5.3.2.1. oxygen has 8 protons
1.5.3.2.2. hydrogen has 1 proton
1.5.3.2.3. oxygen therefore has a stronger attraction to electrons
1.5.3.2.4. this results in oxygen being slightly mor (-) and hydrogen being slightly more (+)
1.5.3.2.5. the molecule is still neutral but the electrons are drawn in an uneven matter
1.5.3.3. permanent dipole is created
1.5.3.3.1. a pair of opposite charges that are always separated by a fixed distance and are permanently aligned
1.6. Conservation Of Charge
1.6.1. the nett charge of an isolated system stays constant during any physical process
1.7. The Unit and Symbol of Charge
1.7.1. Q = electric charge - coulombs C
1.7.2. Proton = +1,6 x 10^-19
1.7.3. Electron = -1,6 x 10^-19
1.8. Quantisation of Charge
1.8.1. an object has an electric,e charge that am interference multiple of the elementary charge: 1,6x10^-19
2. Transverse Pulses
2.1. Terminology
2.1.1. Transverse Pulse
2.1.1.1. when particles of a medium move perpendicular to the propagation direction of the medium
2.1.2. Pulse
2.1.2.1. a single disturbance in a medium that moves from one point to another
2.1.3. Medium
2.1.3.1. material along which a pulse moves
2.1.4. Rest Position / Equilibrium
2.1.4.1. position in a medium when no pulse is moving through it
2.1.5. Amplitude
2.1.5.1. maximum displacement of a particles from its rest position
2.1.6. Pulse Length
2.1.6.1. distance from the starting point of the pulse to the end
2.1.7. Pulse Speed
2.1.7.1. distance the pulse travels per time
2.1.8. Superposition
2.1.8.1. algebraic sum of the amplitudes of 2 pulses that occupy the same space at the same time
2.1.9. Interference
2.1.9.1. Constructive
2.1.9.1.1. phenomenon when the crest of one wave overlaps with the crest of another wave to produce a wave of increased amplitude
2.1.9.2. phenomenon where similar waves with a regular phase relationship goes through the same region at the same time
2.1.9.3. Destructive
2.1.9.3.1. phenomenon where the crest of one wave overlaps with the trough of another wave, resulting in a wave of reduced amplitude
2.2. Diagrams Indicating :
2.2.1. x and y axis
2.2.2. Pulse Length
2.2.3. Amplitude
2.2.4. Equilibrium
2.3. Superposition
2.3.1. Diagrams
2.3.1.1. Constructive
2.3.1.2. Destructive
3. Transverse Waves
3.1. Terminology
3.1.1. Transverse Wave
3.1.1.1. wave in which the disturbance is perpendicular to the propagation direction of the wave
3.1.2. In Phase Points
3.1.2.1. two points in a wave that move in the exact same way at the same time
3.1.3. Peak / Crest
3.1.3.1. highest point in a wave
3.1.4. Trough
3.1.4.1. lowest point in a wave
3.1.5. Frequency 𝒻
3.1.5.1. number of whole waves that move past a fixed point in one second
3.1.5.2. measured in Hertz (Hz)
3.1.6. Period T
3.1.6.1. time taken for one complete coco of an oscillation
3.1.6.2. measured in seconds (s)
3.1.7. Wave Speed v
3.1.7.1. distance travelled by a point on a wave per unit time
3.1.7.2. measured in ms⁻1
3.1.7.3. v = f x λ
3.1.8. Wave Length λ
3.1.8.1. distance between 2 successive points in a wave in phase
3.1.8.2. measured in meters (m)
4. Electro-Magnetic Radiation
4.1. Terminology
4.1.1. Electro-Magnetic Waves
4.1.1.1. a stream of photons that has particle properties and are indivisable
4.1.2. Diffraction
4.1.2.1. bending of waves around the edge of a barrier
4.1.3. Interference
4.1.3.1. when 2 or more wave fronts move over each other and are superimposed on each other
4.1.4. Polarization
4.1.4.1. deafening of waves by the wave vibrations in a certain plane
4.1.5. Photo-Electric Effect
4.1.5.1. when ultraviolet light causes electrons to be released out of some materials
4.1.6. Quantisation
4.1.6.1. a quantity consisting of quantities that cannot be made smaller (these quantities are called quantum)
4.1.7. Quantum
4.1.7.1. indivisible amount of a physical quantity
4.1.8. No material is needed for the propagation of EM radiation
4.1.9. Travels at 3x10⁸ ms
4.2. E = hf or E = hc/λ
4.2.1. E = energy of the photon and is measured in Joules (J)
4.2.2. h = 6,63 x 10^-34 J
4.2.3. f = frequency and measured in Hz
4.2.4. c = 3 x 10^8 ms-1
4.3. Has a dual nature
4.3.1. Particle Nature
4.3.1.1. Photo Electric Effect
4.3.1.2. Particle of light is called a photon
4.3.1.3. Since photons interact with matter, this proves that light has a particle nature
4.3.2. Wave Nature
4.3.2.1. Diffraction
4.3.2.2. Polarisation
4.3.2.3. Interference
4.4. Source
4.4.1. Produced by accelerating electrical charges which produce a changing magnetic field and electrical field that vibrate perpendicular to each other
4.5. Types
4.5.1. Radio Waves
4.5.1.1. radio broadcasts
4.5.1.2. communication
4.5.2. Microwaves
4.5.2.1. heats the water molecules in food
4.5.2.2. satellite communication
4.5.3. Infrared
4.5.3.1. remote controls
4.5.3.2. navigation
4.5.4. Visible Light
4.5.4.1. production of food by plants
4.5.4.2. enables us to see things around us
4.5.5. Ultraviolet (UV)
4.5.5.1. lighting
4.5.5.2. detect forged bank notes
4.5.6. X-Rays
4.5.6.1. CT scans
4.5.6.2. security checks
4.5.7. Gamma Rays
4.5.7.1. kills cancer cells
4.5.7.2. sterilise food and equipment
4.6. Penetrating Ability of EM Radiation
4.6.1. Visible Light
4.6.1.1. reflects off the bodt
4.6.2. UV
4.6.2.1. Skin
4.6.2.1.1. UVA and UVB damages the collagen fibres which results in speeding up skin aging
4.6.2.1.2. UVA is leat harmful but can lead to DNA damage and possible skin cancer
4.6.2.2. Eyes
4.6.2.2.1. high intensity UVB can damage the eyes and exposure may lead to cataracts and other medical issues
4.6.3. X-Rays
4.6.3.1. can lead to cell damage and cancer
4.6.4. Gamma Rays
4.6.4.1. due to high energy levels of gamma rays, the rays can cause serious damage when absorbed by living cells
4.6.4.2. they aren’t stopped by the skin and can change DNA
4.6.5. Cell Phones and Micro Radiation
4.6.5.1. studies sure still being done
4.7. Particle Nature of EM Radiation
4.7.1. energy can quantised (found in photons)
4.7.2. photons are inversely proportional to wavelength
4.7.3. photons are directly proportional to frequency
5. Sound Waves
5.1. Terminology
5.1.1. Sound Wave
5.1.1.1. mechanical wave that propagates through a medium, produced by vibrations and transfers energy
5.1.2. Echoes
5.1.2.1. sound wave created when a it’s reflected off a hard surface like a cliff or wall
5.1.3. Reverberation
5.1.3.1. when the gap between the echoes is small and the 2 sounds merge into 1
5.2. Influences
5.2.1. Air (20C) = 340 ms Water = 1 500 ms Steel = 5 900 ms
5.2.2. Temperature : higher = faster Humidity : higher = faster Pressure : no changes occur
5.3. Properties of Echoes
5.3.1. Can be reflected by a hard surface
5.3.2. Angle of (i) = Angle of (r)
5.4. Why do waves move faster in solids?
5.4.1. The particles in a solid are closely packed, allowing them to transmit vibrations quicker than in liquids or in gases
5.5. Can sound move through a vacuum?
5.5.1. No, sound requires a medium to transmit energy and upon a vacuum there are no particles/ no medium, therefore sound cannot move through a vacuum
6. Longitudinal Waves
6.1. Terminology
6.1.1. Longitudinal Waves
6.1.1.1. wave in which the disturbance from its equilibrium is parallel to the propagation direction of the wave
6.1.2. Compression
6.1.2.1. region of high pressure in a longitudinal wave
6.1.3. Rarefaction
6.1.3.1. region of low pressure in a longitudinal wave
6.1.4. Loudness
6.1.4.1. strength of the ear’s perception of a sound
6.1.4.2. directly proportional to amplitude
6.1.5. Pitch
6.1.5.1. effect produced in the ear due to the sound of a particular freauency
6.1.5.2. directly proportional to frequency
6.1.6. Ultrasonic
6.1.6.1. ultrasonic vibrations have frequencies higher than 20 000Hz
6.2. Diagrams Including:
6.2.1. wavelength
6.2.2. compression
6.2.3. rarefaction
6.2.4. propagation direction