P5.1 grey - new Flashcards
Incl some non-greybits
There are 2 ways to represent a wave
1 - a time trace shows how displacement varies with time at a particular position
2 - a snapshot of a wave shows how displacement varies with distance at a particular time
Time trace - time for a wave to complete one oscillation is?
/ point for a wave to same point on next wave
Time period of the wave
Snapshot - distance from one point on a wave to the same point on the next is?
Wavelength
Amplitude in time trace / snapshot
Middle to the top/bottom(trough) of a wave
To measure the velocity of sound - clap
Time how long it takes to hear an echo of a clap when yo are at a distance from a wall , work out velocity - distance, velocity, time
To measure the velocity of sound - alternate
Connect a pair of microphones a certain distance apart to an oscilloscope
- know the distance between the microphones and the time for the sound to travel between them to calculate velocity
As sound is a longitudinal wave, when you see the trace of a transverse wave on the screen of an oscilloscope, it is showing ?
Variation of pressure with time, not the sound wave itself
The velocity of sound can vary w/ (2) and why
- temperature and pressure
- this is because these factors affect the velocity at which the disturbance in the wave is transferred between particles
3 wave phenomena
Reflection - waves reverse direction
Refraction - waves change direction/bend
Diffraction - waves spread out
Medium
(Plural media) is a region of space of the same material/density
Wave phenomena only occur when (2)
- at the boundary between 2 media
- when a wave changes speed
When waves cross a boundary, what changes, what doesnt
- speed will change
- frequency never changes
- wavelength will change
(According to wave equation, as speed changes)
Reflection - definition
Reflection is the wave phenomenon by which a wave reverses direction as it meets the boundary between two media.
Reflection - rules
(2)
We always consider plane (smooth) surfaces such as mirrors, which obey the law of reflection.
“The angle of incidence, i is equal to the angle of reflection, r”
i = r
PIC
Reflection - 1 line, 2 rays, 2 angles
W/ray diagram
.
Plane mirror
A mirror which is perfectly flat( and reflects all of the light incident upon it)