Waves Flashcards
What is a wave?
Something that transfers energy without transferring matter
What is lamda?
Wave length
What is wavelength?
The length of a full cycle of the wave - from peak to peak
What is amplitude?
The maximum height of the wave from displacement point
What is frequency?
How many complete wave cycles there are per second (measured on Hz)
What is the period?
The number of seconds it takes for one full cycle
period = 1 divided by frequency
What is the equation for wave velocity?
Wave velocity = frequency x wave length
Wave speed = distance/ time
What are transverse waves?
When the oscillations (vibrations) are perpendicular to the direction the wave travels
What are some examples of transverse waves?
- all electromagnetic waves
- S-waves
- ripple and waves in water
What are longitudinal waves?
When the oscillations are parallel to the direction the wave travels
-they squash and stretch the arrangement of particles in the medium they pass through making compressions and rarefactions
What are some examples of longitudinal waves?
- sounds waves
- P-waves
When and what does refraction happen?
Retractions happens when a wave changes from one medium to another. This caused the wave to change direction (looks like it has been bent)
What is a medium?
What the wave is travelling through -this can be a gas, solid,liquid or vacuum
What is the normal line?
A line 90° from the surface
When a wave crosses a boundary why does it change speed?
As different densities result in different speeds
What happens if a wave hits a boundary at an angle?
The change of speed causes a change in direction (refraction
What happens when a wave is travelling along the normal?
It will change speed but it is not refracted so will leave at the same angle it enters
What happens when there is a greater change in speed?
The great change in speed the more a wave bends
- if it speeds up it moves away from the normal line
- if it slows down if bends towards the normal line
What is direct proportion?
When something goes up the other goes up in proportion - a correlation between two things where their ratio is constant
What is the law of reflection?
Angle of incidence = Angle of reflection
What is the angle of incidence and reflection?
- The angle between the incoming wave and the normal (AOI)
- the angle between the reflected wave and the normal (AOR)
What are the first 3 stages of the investigating refraction experiment?
- place a rectangular glass block in a piece of paper and trace around it using a ray box to shine a ray of light through the middle of one side of the block
- trace the incident and emergent ray on the other side of the block
- remove the block and join the incident and emergent ray with a straight line to measure the refracted ray
What are the 4th,5th and 6th stages of investigating refraction?
Draw the normal and the point where the ray entered the block and use protractor to measure the ray of incidence and refraction
- do the same for the point where the ray emerges from the block
- do this 3 times and calculate and average for the angles
What should the outcome of investigating refraction experiment be?
- as it enters the block the ray of light should bend towards the block (AOR is less than AOI) because the air has one of the lowest optical densities meaning light slow down
- as it leaves the block the ray should bend away from the normal as the light ray speeds up as it travels through air
What happens to waves at boundaries?
- The may be absorbed by the second material (transfer energy to the material’s energy stores)
- transmitted where it travels through the second medium
- reflected when the incoming ray is neither absorbed or transmitted but instead is sent back away from the second material
What is refraction?
When a wave changes speed and direction at a boundary
