P12 - Waves Flashcards
What is an ultrasound wave?
Sound wave at a frequency greater than 20,000 Hz (the upper frequency of the human ear)
What is amplitude
- Height of wave crest or trough from rest position (transverse wave)
- Closeness of coils in compression (longitudinal wave)
What is compression?
Squeezing together
What is an echo?
A reflection of sound that can be heard
What are electromagnetic waves?
Electric and magnetic disturbances that transfer energy from one place to another
What is frequency?
The number of waves passing a fixed point every second
What are longitudinal waves?
Waves in which the vibrations are parallel to the direction of energy transfer
What are mechanical waves?
vibrations that travel through a substance
Define Oscillate:
move to and fro about a certain position along a line
What is a Primary Seismic Wave (P-wave)?
Longitudinal waves that push or pull on the material that they move through as they travel through the earth
What is rarefaction?
Stretched apart
What is reflection?
The change of direction of a light ray or wave at a boundary when the ray or wave stays in the incident medium
What is refraction?
The change of direction of a light ray when it passes across a boundary between 2 transparent substances at a non-zero angle
What is a Secondary Seismic Wave (S-wave)?
Transverse waves that shake the earth side to side as they pass through
What are seismic waves?
Seismic waves are waves that travel through the earth, they are produced in an earthquake and spread out from the epicentre
What is wave speed?
The distance travelled by a wave every second
What is transmission/transmitted?
A wave passing through a substance
What is a transverse wave?
A wave were the vibration is perpendicular to the direction of energy transfer
What is a vibration?
Oscillate rapidly about a certain position
What is a wavelength?
The distance from one wave crest to the next
What is the period of a wave?
The time taken for 2 successive crests (1 wavelength) to pass a fixed point
What is a wave?
A series of oscillations that travel from one place to another, transferring energy
What is a wave crest?
The highest point above the reset point
What is a wave trough?
The lowest point below the reset point
What is the unit for frequency?
Hertz (Hz)
What is the equation for the period of a wave?
T (period) = 1 / f (frequency)
What is the equation for the speed of a wave?
V (speed of wave) = f (frequency) × λ wavelength)
What is the normal line?
The normal is a dotted line drawn perpendicular (90°) to the surface of the material, at the point of entry of the light.
What is the law of reflection
The reflected waves move away from the flat barrier at an angle equal to the incident waves (The angle of incidence = the angle of reflection)
What is the angle of incidence?
The angle between the normal and the incident ray
What is the angle of reflection?
The angle between the normal and the reflected ray
What is the incident wave?
The wave travelling towards a barrier or boundary
What is a reflected ray?
A ray of light that has been reflected off a surface
What is a refracted ray?
A ray that travels in another medium and undergoes a change of velocity
What is the equation for the distance of an object detected using sound?
Distance (m) = 1/2 x speed of wave (m/s) × time (s)
Explain how a light wave will be refracted depending on the material that it enters
- Light wave enters more dense medium:
- Slows down (more resistance)
- Bends towards the normal
- Light wave enters less dense medium:
- Speeds up (less resistance)
- Bends away from the normal
How would you demonstrate a mechanical longitudinal wave?
Pulling a slinky forwards and backwards
How would you demonstrate a mechanical transverse wave?
tying 1 end of a rope to a fixed position and moving the other end up and down
What medium do mechanical waves travel through fastest?
Solids
What medium do electromagnetic waves travel through fastest?
a vacuum