PHYSICS - waves

waves

a means of transferring energy from place to place without transferring matter

wave length

distance between 2 consecutive points

cm/m

lamda

amplitude

the max distance of a point on a wave from the equilibrium

units vary

A

period

the time taken for one complete cycle

Secs

T

frequency

number of complete cycles that pass in 1 sec

Hz

F

wavefront

imaginary line running along the crest of a wave

Transverse waves

waves in which the vibrations(oscillations)are perpendicular to the direction waves are travelling

• light

• radiation

• s waves

• microwaves

Longitudinal waves

waves in which the vibrations(oscillations)are parallel to the direction waves are travelling - all need a medium to travel

• sound waves

• P waves

refraction

the bending or changing direction of a wave, like light, when it travels from one medium to another

slows down when region is more dense

EM waves

• Transfer energy

• reflect and refract

• don’t transfer matter

• travel through a vacuum at the same speed

• 3 × 10⁸ m/s

• are transverse

Doppler effect

A change in frequency and wavelength when the object and observer are moving relative to eachother

• towards observer = decreased wavelength and increased frequency

7 types of EM waves

Radio

Microwave

Infrared

Visible light

Ultra violet

x-ray

Gamma rays

radio

Uses - Communication, naviagation

Dangers - Nothing in normal doses

Microwaves

Uses - Communication, cooking food, radios/satellite

Dangers - Internal heating of body tissues

Protections - Metal screens in ovens

Infrared

Uses - Night vision, remote controls, heaters

Dangers - Skin damage, surface burns to skin

Protection - protective clothing

visible light

Uses - Sight/ vision, communication

Dangers - Eye damage

Protection - avoid looking at intense light directly

Ultraviolet

Uses - Sterilization, fluorescence, tanning beds, killing bacteria

Dangers - eye/skin damage, skin cancer

Protection - sunglasses, sunscreen

x-ray

Uses - Medical imaging, security scanning

Dangers - cell mutations/damage, cancer - Ionising celss

Protection - lead apron/ shielding, minimal exposure

Gamma Rays

Uses - Cancer treatment, sterilizing medical equipment

Dangers - Cell mutations/damage, cancer - ionising cells

Protection - Lead shielding, minimal exposure