unit 1: physics Flashcards
what does oscillation mean
repetitive motion
what’s a complete oscillation
travelling from one side to the opposite side and back to the original position
what is period time
time for one complete cycle
1/F
what is amplitude
maximum displacement always measured from the centre
what’s wavelength
distance between two consecutive points where oscillations are in phase with one another
travelling one wavelength takes how many cycles?
one
when energy is being transferred , is matter transferred?
no
in a longitudinal wave how do oscillations travel?
back and forth along the direction of propagation
in a transverse wave how do oscillations travel
at right angles to the direction of propagation - up and down or side to side
in longitudinal waves what do the oscillations cause
compressions and rarefactions
what does compression mean?
particles are close together
what does rarefactions mean
particles are far apart
how does thicker stringers effect the speed and note
slower speed and a lower note
how does tighter strings effect the note and speed
faster speed and a higher note
what is the speed of light
2.998 x 10^8 ms-1
does light travel slower or faster in liquid and gas
slower
what does the equation c/v = n give
refractive index of a medium
what are wave fronts
- lines drawn to join points in a wave where all of the oscillations are in phase
-spaced one wavelength apart
-move forward in a direction that is perpendicular to the wave front
what is interference
a detectable pattern of different strengths of wave oscillations
what is superposition
waves from two different sources that cross and their amplitudes are added together
how is path difference created
dividing a light source so that separate rays of light travel at different paths
what does path difference create
phase difference
how does the path difference increase
as the angle through which a grattings caters the light is increased
what happens when the path difference equals a whole number
the light rays will be in phase and constructive interference ( a bright fringe) will occur
what happens when light has a mixture of wavelengths
condition for constructive interference occurs at different angles for each wavelength so a set of coloured lines is produced
what are stationary waves
two progressive waves moving in opposite directions and superimposed one on the other.
what is the result of two stationary waves
fixed pattern of antinodes and nodes
what is a resonator
store wave energy by reflecting the wave back on itself to form a stationary wave pattern
when are resonators efficient
only receive energy from a source that has a frequency close to one of their own natural frequencies which is called resonance.
what waves do string instruments use in stretched strings
stationary waves to make a resonator
the fixed ends of strings are?
nodes
what instruments use longitudinal waves
pipe organs , woodwind , brass
open ends of pipes are?
antinodes
what are optical fibres?
high density glass that can carry light signals long distances without loosing any light through their sides
what is the critical angle
least angle of incidence at which total internal reflection occurs
when does the critical angle apply
when light tries to leave an optically dense medium at a boundary into a less dense medium
