Waves Flashcards
What do waves transfer?
Energy and information
What are the two types of waves?
Transverse and longitudinal
What is a transverse wave?
A wave for which the oscillations are perpendicular to the direction of energy transfer
What is a longitudinal wave?
A wave for which the oscillations are parallel to the direction of energy transfer
What are some examples of transverse waves?
Electromagnetic waves and seismic s-waves
What are some examples of longitudinal waves?
Sound waves and seismic p-waves
What are the two parts of a longitudinal wave called?
Compressions and rarefaction
What are the two parts of a transverse wave called?
Peaks and troughs
What is a waves amplitude?
The maximum displacement of a point on a wave from its undisturbed
What is wavelength?
The distance from a point on a wave to same position on the adjacent wave and most commonly peak to peak or trough or trough
What is the frequency of a wave?
The number of waves that pass a given pint each second
What is the unit used for frequency?
Hertz
What is meant by a frequency of 200Hz?
200 waves pass a given point each second
What is wave speed?
The speed at which energy is transferred through a medium
What does a wave transfer?
Energy
What is wave velocity?
It’s equal to the product of the wavelength and frequency of the wave
What is the equation for wave speed?
Frequency x wavelength
What is meant by the period of the wave?
The length of time it takes for one full wave to pass through a point
How do sound waves travel through a solid?
The particles in solid vibrate and transfer kinetic energy through the material
How does the human ear work?
The outer ear collects the sound which travels into the ear, the sound waves cause the eardrum to vibrate at the same frequency, this is amplified by three ossicles (small bones), this causes the hair in the cochlea to vibrate, the cochlea converts the vibration into electrical signals, the signals are passed to brain through the auditory nerve and the brain converts the electrical signal into sound
What is the frequency range of human hearing?
20 Hz - 20kHz
What is an ultrasound wave?
A sound wave with a frequency greater than 20,000 Hz
What sound of frequencies less than 20Hz called?
Infrasound
What natural event causes seismic waves to be produced?
Earthquakes, produce both P-waves and S-waves
Are P-waves transverse or longitudinal?
Longitudinal
Are S-waves transverse or longitudinal?
Transverse
What is the difference between the mediums that P-waves and S-waves can travel through?
P-waves travel through both solids and liquids whereas S-waves only travel through solids
What significance of P and S waves?
They provide evidence that the Earth has a liquid core; only P waves produced by an earthquake can be detected on the other side of the globe
What technique is used to detect objects in deep water and measure water depth?
Echo sounding, high frequency sound waves are emitted, reflected and detected and time difference between emission and detection, alongside wave speed are used to calculate distance
How does sonar work?
When ultrasound waves are emitted they reflect off boundaries and their echoes are detected, the speed of the ultrasound is known and also the time it takes to detect the echoes, the equation of distance is used to find the distance travelled and distance travelled is halved to give the distance between emitter and boundary
How does foetal scanning work?
An ultrasound wave is sent into the patient body, it passes through the body and reflects off the organs and tissues, the device then uses the reflected ultrasound waves to produce an image of the foetus and the ultrasound is safe and therefore doesn’t damage cells
What word is used to describe when a wave bounces off a surface?
Reflection
What is the normal?
A vertical imaginary line which is perpendicular to the boundary
What occurs when light is reflected off a boundary?
It bounces off a smooth flat surface so that the angle of incidence is same as the angle of reflection
What is refraction?
Refraction is the change in speed of a wave as it reaches a boundary between two media, usually resulting in a change in direction
What occurs when light is refracted at the boundary?
The light changes speed and direction in the new medium, if the new medium is more dense, the light will travel slower and bends the normal and if the new medium is less dense, the light will travel faster and bend away from the normal
What happens to light waves when entering denser materials?
They slow down and bend towards the normal
What happens to light waves when entering less dense materials?
They sped up and bend away from the normal
How can refraction be measured?
The angle of incidence and angle of refraction can be measured and compared, all angles are measured relative to the normal
What are the effects of absorption of different wavelengths of waves in different mediums?
Some materials behave differently depending on the wavelength
How do sound waves travel through a solid?
The particles in a solid vibrate and transfer KE through the material
