VCE Physics Unit 1 AOS 1

Wave

A transmission of energy through periodic oscillations without transferring matter

Oscillation

Repeated back-and-forth motion about a central position

Propagation

The movement of a wave through a medium or space

Vacuum

A region with no matter where electromagnetic waves can travel

Mechanical Wave

A wave that requires a medium to propagate (e.g., sound, water waves)

Electromagnetic Wave

A wave that can travel through a vacuum and consists of oscillating electric and magnetic fields

Transverse Wave

A wave where oscillations are perpendicular to the direction of energy transfer (e.g., light, water waves)

Longitudinal Wave

A wave where oscillations are parallel to the direction of energy transfer (e.g., sound, seismic P-waves)

Amplitude

The maximum displacement of a wave from its equilibrium position

Wavelength (λ)

The distance between two identical points on a wave (e.g., crest to crest)

Period (T)

The time taken for one complete wave cycle to pass a point

Frequency (f)

The number of complete wave cycles per second, measured in Hertz (Hz)

Wave Equation

v=fλ (Velocity = Frequency × Wavelength)

Reflection

The bouncing of a wave off a surface

Law of Reflection

The angle of incidence equals the angle of reflection (𝜃1 = 𝜃2)

Refraction

The bending of a wave as it enters a new medium due to a change in speed

Refractive Index (n)

A measure of how much light slows down in a medium (𝑛 = 𝑐/𝑣)

Snell's Law

𝑛1sin𝜃1 = 𝑛2sin𝜃2, describes how light bends at a boundary

Total Internal Reflection (TIR)

When light is completely reflected within a medium rather than passing through

Critical Angle

The angle at which total internal reflection occurs (sin𝜃 = 𝑛2/𝑛1 )

Electromagnetic Spectrum

The full range of electromagnetic waves arranged by wavelength and frequency

Radio Waves

Longest wavelength, used for communication and broadcasting

Microwaves

Shorter than radio waves, used in Wi-Fi, radar, and cooking

Infrared (IR)

Perceived as heat, used in thermal imaging and remote controls

Visible Light

The part of the spectrum detectable by the human eye

Ultraviolet (UV)

High-energy waves used for sterilization and can cause sunburn

X-rays

High-frequency waves used in medical imaging

Gamma Rays

Highest energy waves, used in cancer treatment and nuclear reactions

Dispersion

The separation of white light into its component colors due to refraction

Rainbow Formation

Caused by refraction, dispersion, and total internal reflection inside raindrops

Mirage

An optical illusion caused by light bending due to air temperature differences

Inferior Mirage

A mirage where the image appears below the object, caused by hot surfaces

Superior Mirage

A mirage where the image appears above the object, caused by cold air over warm air

Optical Fiber

A thin glass core that uses total internal reflection to transmit light for communication

Absolute Zero

The lowest possible temperature (0 K or -273.15°C) where particles have zero kinetic energy

Kelvin Scale

Absolute temperature scale where 0 K corresponds to absolute zero and no negative values exist

Heat

The transfer of thermal energy from a hotter object to a cooler object due to a temperature difference

Second Law of Thermodynamics

Heat naturally flows from hot to cold unless work is done to reverse it

Conduction

The transfer of heat through direct contact via particle collisions, mainly in solids

Why Metals Conduct Heat Well

Free electrons in metals move and transfer energy quickly

Why Wood is an Insulator

Electrons are tightly bound, and air pockets reduce heat transfer

Convection

The transfer of heat in fluids (liquids & gases) due to density differences, forming currents

Why Convection Happens

Heated fluid expands, becomes less dense, rises, while cooler fluid sinks

Thermal Radiation

The transfer of heat via electromagnetic waves (infrared), which does not require particles

Why Black Absorbs More Heat

Darker colors absorb more infrared radiation, while white reflects it

Specific Heat Capacity (SHC)

The energy required to raise the temperature of 1 kg of a substance by 1 K

Formula for Heat Energy

Q=mcΔT, where

Q = heat energy,

m = mass,

c = SHC,

ΔT = temperature change

Why Different Materials Heat Differently

Different substances store and transfer heat energy in unique ways

Latent Heat

The energy required to change the state of a substance without changing its temperature

Why Temperature Stays Constant During Phase Change

Energy is used to break or form molecular bonds instead of increasing kinetic energy

Formula for Latent Heat

Q=mL, where

L is latent heat of fusion

Why Vaporisation Requires More Energy Than Fusion

More energy is needed to fully break intermolecular bonds in a liquid-to-gas transition

Evaporative Cooling

High-energy particles escape from a liquid's surface, lowering its average kinetic energy and causing cooling

Formula for Combined Heat and Phase Change

𝑄(total) = mcΔT+mL, used when temperature change and phase change occur together

Temperature

Measure of the average translational kinetic energy of particles in a substance