P1P4 - Waves Flashcards
What do waves do?
Waves transfer energy from one place to another without transferring matter.
What is a transverse wave?
Particles that vibrate at right angles to the direction of the wave’s motion.
What are some examples of a transverse wave?
Moving springs
Mexican wave
Bobbing cork
Water
What is a longitudinal wave?
Particles that vibrate in the same direction as the wave’s motion
What are some examples of a longitudinal wave?
Sound waves
P-waves
Pulling/pushing springs
How do you calculate frequency?
frequency = number of oscillations ÷ time
What is frequency?
The number of oscillations per second.
What are oscillations?
Vibrations
What is defined as the greatest distance a point on the wave moves from its rest position?
Amplitude
What is the ‘period’ in a wave?
The time taken to complete one oscillation.
In a transverse wave, what is the wavelength?
The distance between 2 peaks of adjacent waves.
Whats the best way to observe waves?
A ripple tank
How does a ripple tank work?
A rod at one end of a tank of water creates a series of ripples.
A bright light shone through the water onto a sheet of paper shows the ripples on the water very clearly as a series of parallel lines travelling along with constant speed.
These parallel lines are the peaks of the ripples on the water. We call them wavefronts.
What is the distance between two wavefronts?
Wavelength
How do you calculate wavespeed?
Wavespeed =
Frequency X Wavelength
What quantities are unchanged at a boundary?
Frequency
What quantities are changed at a boundary?
Wavelength
Wavespeed
What can waves do when it passes a boundary?
Can be reflected,
refracted,
absorbed,
transmitted
What is the angle of incidence?
The angle between the incident (incoming) light ray and the normal.
What is the angle of reflection?
The angle between the reflected light ray and the normal.
What is the law of reflection?
The law of reflection states that the angle of incidence = the angle of reflection.
What is the medium of a wave?
The material through which a wave travels through
What is compression?
Medium is squashed together
What is rarefaction?
Medium is stretched apart
What are the range of frequencies we can hear?
20Hz - 20,000Hz
What is ultrasound?
Soundwaves above 20k Hz
What is infrasound?
Soundwaves below 20Hz
What are the speeds of sounds in the 3 states?
Solid - Highest
Liquid - Higher
Gas - Lowest
Information from the ear is sent to the brain via what?
The auditory nerve
How are sound waves detected and heard in the ear?
Sound waves are detected by making the ear drum vibrate.
This signal is passed via the small bones (hammer, anvil and stirrup) to the auditory nerve.
This sends an electrical signal to the brain.
WHat are the 3 bones in the ear?
(hammer, anvil and stirrup)
How can we use echo to measure water length?
We send an ultrasound pulse into the water.
When this pulse hits any surface, it is reflected back.
We can work out the distance travelled by the sound wave by:
recording the time between us sending the pulse and detecting the reflection.
How do we use ultrasounds to perform a scan?
Ultrasound waves can pass through the body.
When they reach a boundary between two different materials, some will be reflected.
We can detect the reflected waves.
A computer processes the timing and distribution of these waves. The computer uses these to produce a video image of the foetus.
What are the 2 waves earthquakes produce?
P-waves (Primary)
S-waves (Secondary)
What are p waves?
Longitudinal seismic waves
Can travel at diff speeds through solids and liquids
What are s waves?
Transverse seismic waves
Can only travel through solids
How did scientists work out earth has a solid core surrounded by a liquid outer core?
By detected seismic waves
