P1 5 Waves Flashcards
What are the two different types of waves?
Mechanical waves and electromagnetic waves
What can we use waves for?
To transfer information and transfer energy.
What are mechanical waves? Give an example for this.
They are waves that need a medium to travel through such as sound waves and water waves.
What are electromagnetic waves? Give an example for this.
They are waves which can travel through a vacuum therefore no medium is needed. For example light waves and radio waves.
What speed do all electromagnetic waves travel at?
300000 kilometres per second
What do vibrations in transverse waves travel like?
They are perpendicular to the direction in which the wave transfers energy.
What do vibrations in a longitudinal travel in?
They travel parallel to the direction in which the waves are travelling.
What are compressions and rare fractions in a longitudinal wave? How do they relate to the air particles surrounding the vibrations?
Compressions are places in the wave squashed together.
Rare fractions are places in the wave further apart.
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What are all electromagnetic waves?
Transverse waves
Give an example of a longitudinal wave.
Sound waves
What are the two categories of a mechanical wave?
Longitudinal and transverse.
Why do we need to measure waves?
To find out how much energy or information they carry.
What is the top of a wave called?
Crest or peak
What is the bottom of a wave called?
Troughs
What is the amplitude of a wave?
The height of the wave crest or the depth of the awe trough from the middle.
What is the wave’s position at rest?
The middle of it
If the amplitude increases what happens to the energy carried by the waves?
It increases too.
What is the wavelength of a wave?
The distance from one wave crest to the next.
What is the frequency if a wave?
The number of wave crests passing a fixed point every second.
What is the unit of frequency?
Hertz (Hz)
What are straight waves called?
Plane waves
What are the properties of plane waves?
They move at the same speed and keep the same disgrace apart.
What is the wave speed?
The distance travelled by a wave crest or a wave trough every second.
What does the wave speed depend on?
The frequency and wavelength.
What is the equation to find the wave speed?
Wave speed (m/s) = frequency (Hz) x wavelength (m)
What is the wave equation in symbols?
V = f x (lamda sign)
What is the perpendicular line to the mirror called?
The normal.
What is the angle of incidence?
The angle between the incident ray and the normal.
What is the angle of reflection?
The angle between the reflected ray and the normal.
What does the law of reflection state?
- The angle of incidence is equal to the angle of reflection.
- The image is virtual.
- The image is laterally inverted.
What is refraction?
The change of direction of waves when they travel across a different medium.
Are waves slower or faster on shallow water?
Slower
What happens when the waves are not parallel to the boundary?
They change direction.
When is the wave drawn towards the normal?
When it crosses form deep to shallow
What is the wave drawn away from the normal?
When it crosses from shallow to deep.
How does the angle of defection change?
When a wave changes direction towards the normal, then the angle of refraction is smaller than the angle of incidence and vice versa.
What does white light contain?
All the colours of the spectrum
What is diffraction?
The spreading out of waves when they pass through a gap or past the edges of an obstacle.
The narrower the gap…?
The more the waves spread out.
The wider the gap…?
The less the waves are spread out.
Can all waves be diffracted? Both longitudinal and transverse? Why is diffraction in light not very distinct?
Yes, light waves have very small and narrow wavelengths therefore they need very small gaps in order to diffract?
What will happen when radio waves aren’t diffracted well over a hill?
There will be poor reception.
