Waves

Oscillation

An oscillation is a movement back and forth about a fixed point

Equilibrium

The resting position of an object when no force is making it move

Period

Time taken for one particle to complete a whole oscillation.

Same as the time taken to complete a whole wave

Frequency

The number of complete waves or vibrations that pass a point every second

Hertz

The unit used to measure frequency

If one cycle is completed in a second => frequency is 1 hertz

Equation for frequency

frequency (F) = 1/period (T)

Amplitude

The maximum displacement of a wave from its rest (equilibrium) position

Wave

Transfer of energy from one point to another without the transfer of matter

Peaks(High) Troughs(Low)

Points of maximum amplitude

Wavelength

The distance between two identical points on consecutive waves

Measured in metres (m)

Symbol: λ (lambda)

Transverse wave

When the oscillations are perpendicular to the direction of energy transfer

(the direction the wave is moving in)

Longitudinal waves

When oscillations are parralel to the direction of energy transfer
(the direction the wave is moving in)

Period

The distance between 2 successive peaks or throughs

measured in metres

Wave speed

The speed at which a wave is travelling

measured in m/s

Compression

Section of a longitudinal wave in which the matter has bunched together

Rarefaction

Section of longitudinal wave in which the matter has spread apart

Sound wave contain:

High pressure section called compressions

where the particles are all close together

Low pressure section called rarefactions
where the particles move apart from each other

Examples of longitudinal waves

Sound waves

P-waves during earthquakes

Examples of transverse waves

Light + all of the other electromagnetic waves

Water waves

Magnitude of displacement

How far a particle is from equilibirum

Wave speed equation

wave speed(v))=frequency(Hz) x wavelenght

Units for wave speed equation

Wave speed= m/s

Wavelenght=m

Frequency=Hz

Period=s

Electromagnetic waves

All are transverse:

• Radio

• Microwaves

• Infrared

• Visible light

• Ultraviolet

• X-rays

Mechanical waves

Need a medium to travel:

• Sound

• Water

• Seismic waves

Symbols

• Wavelength (λ) → distance between matching points on waves.

• Frequency (f) → number of waves per second, measured in Hz.

• Amplitude → maximum displacement from the rest position.

• Wave speed (v) → how fast the wave travels, measured in m/s.

• Period (T) → time for one complete wave.

Properties Electromagnetic waves

• All are transverse.

• Can travel through a vacuum.

• All travel at 3 × 10⁸ m/s in a vacuum.

• Can be reflected, refracted and diffracted

7 parts of electromagnetic spectrum

Radio wave (least)

Microwave

Infrared

Visible light

Ultraviolet

X-Rays

Gamma Waves
(Increasing frequency)

Which color of visible light has the longest wavelenghth

Red

Which color of visible light has the shortest wavelenghth

Purple

Radio waves use

-Long range communication (radio & tv)

Because be reflected off the bottom of the ionosphere enabling them to travel great distances

Microwaves use

2 types:

Are NOT absorb by water molecules:

Satellite communication - Because pass through atmosphere

Absorbed by water molecules:

Microwave/cooking ovens - Because water molecules in food absorbs microwaves

Infrared waves use

-Thermal imaging

Because all objects (regarding temp) emit I.R waves

-Cooking (ovens/grills)

Because emit infrared radiation=> heat is transferred

(example: toasted bread, heat surface)