11. Waves 1 Flashcards
(37 cards)
What is a progressive wave?
An oscillation that travels through matter (in some cases a vacuum)
All progressive waves transfer energy from one place to another but not matter
What happens when a progressive wave travels through a medium?
- The particles in the medium move from their original equilibrium position to a new position
- The particles in the medium exert forces on each other
- A displaced particle experiences a restoring force from its neighbours and it is pulled back to its original position
What is the resorting force?
A force that acts to bring particles back to their equilibrium position after they have been displaced
It arises due to the elastic properties of the medium
What is the difference between transverse and longitudinal waves?
Transverse: The oscillations/vibrations are perpendicular to the direction of energy transfer
Longitudinal: The oscillations/vibrations are parallel to the direction of energy transfer
Examples of transverse waves
- Electromagnetic waves
- S-waves
- Waves on a stretched string
Examples of Longitudinal waves
- P-waves
- Sound waves
What is Displacement?
The distance from the equilibrium position in a particular direction
What is amplitude?
The maximum displacement from the equilibrium position
What is Wavelength?
The minimum distance between two points in phase on adjacent waves
What is the Period of oscillations?
The time taken for one oscillation
or
The time taken for a wave to move one whole wavelength past a given point
What is frequency?
The number of wavelengths passing a given point per unit time
What is wave speed?
The distance travelled by a wave per unit time
What is the wave equation?
v = fy
What is on the axis of a wave profile?
y-axis = displacement
x-axis = distance
When are particles in phase?
When they are oscillating perfectly in step with each other
When are particles anti-phase?
When they are oscillating completely out of step with each other
When are particles out of phase?
When they are neither in phase or in antiphase
When does reflection occur?
When a wave changes direction at a boundary between two different media, remaining in the original medium
What is the law of reflection?
The angle of incidence is equal to the angle of reflection
What happens to wavelength and frequency when waves are reflected?
They both do not change
When does Refraction occur?
When a wave changes direction as it changes speed when it passes from one medium to another
How does the speed effect where the wave refracts?
If the wave slows down it refracts towards the normal
If the wave speeds up it refracts away from the normal
How does wavelength and frequency change when a wave is refracted?
Frequency remains the same
Wavelength changes v=fy, v is directly proportional to y
How is the speed of a wave affected by water depth?
Shallow water: slows down, decreased wavelength
Deep water: speeds up, increased wavelength
