Waves (P6) Flashcards
What does a wave transfer?
Energy from one place to another
What causes a wave?
A vibration
What is the definition of a transverse wave?
Oscillation is perpendicular to the direction of the wave
What is the definition of a longitudinal wave?
Oscillation is parallel to the direction of the wave
Give examples of longitudinal waves
Sound
Ultrasound
Primary Earthquakes (P)
Give examples of transverse waves
Water waves
All EM waves
Secondary Earthquake (S)
What is compression?
A compression is when particles in a longitudinal wave are closest
What is rarefaction?
A rarefaction is when particles in a longitudinal wave are furthest apart
What is amplitude?
The maximum displacement of a wave from its equilibrium
What is wavelength?
The distance from a point in one wave to the same point on the next (i.e.: trough to trough)
What is frequency?
Amount of waves that pass a point every second
What is the unit of wave speed?
m/s
What is the unit of wavelength?
m
What is the unit of frequency?
Hz
Equation for wave speed
v=fλ
velocity = frequency x wavelength
What speed to EM waves travel at?
300, 000, 000 m/s
What speed does sound travel at?
330 m/s
List EM waves from longest to shortest
Radio Microwaves Infra-red Visible Ultra-violet X-ray Gamma
Which EM wave has the highest frequency?
Gamma
Which EM wave has the most energy?
Gamma
Which EM waves are the most ionising?
Ultra-violet, X-rays and Gamma
What happens when light travels from air into a glass block?
Refracts towards the normal
What is the law of reflection?
The angle of incidence is the same as the angle of reflection
What is the danger of ultra violet radiation?
Can cause premature aging of the skin and increased risk of skin cancer
What is the danger of X-rays and gamma rays?
They are ionising radiation that can cause the mutation if genes and cancer
What are radio waves used for?
Television and radio transmissions
What are microwaves used for?
Satellite communication (they can travel through ionosphere) Cooking food
What is infra-red used for?
Electrical heaters
Cooking food
Infra-red cameras
What is visible light used for?
Fibre optic
To see
What is ultra-violet used for?
Energy efficient lamps
Tanning
What are X-rays used for?
Medical imaging
Security scanning
What are gamma rays used for?
Medical treatment (radiotherapy)
What type of wave does compression occur in?
Longitudinal
What type of wave does rarefaction occur in?
Longitudinal
What is the peak of a wave?
Top point
What is the trough of a wave?
Bottom point
When does light refract towards the normal?
When entering a medium denser than the one it was in
When does light refract away from the normal?
When entering a medium less dense than the one it was in
How do we calculate time period?
Period = 1/frequency
Define period
The time it takes for one complete wave
What is a boundary?
Where two substances meet
What happens when light hits a boundary?
It reflects, refracts or is absorbed
What is the normal?
An imaginary line perpendicular to the boundary
Which mediums is light slower through?
Dense
When light enters and leaves a glass block, which angles are the same?
The angle of incidence is equal to the angle between the normal and the light leaving the block
Where do we measure the angle of incidence between?
The normal and the light
What do we call reflection on a flat surface?
Specular Reflection
What do we call reflection on a bumpy/uneven surface?
Diffuse Reflection
