Chapter 14- Nature Of Waves Flashcards
Mechanical
Need a medium for transmission
Generated by vibrating sources
Energy from the vibrations is transferred to the medium and is transmitted by the particles within it
Longitudinal
Oscillations parallel to direction of energy transfer
Transverse
Oscillations of particles perpendicular to direction of energy transfer
Longitudinal vocab of movement
Compressions and rarefractions
Examples of transverse waves
Water waves
Example if longitudinal
Sound waves
Amplitude def
Maximum displacement from the mean position
Metres, m
Period def
Time taken for one complete oscillation
Seconds, s
Frequency def
Number of complete oscillations per second
Hertz, Hz
Frequency eq
f= 1/T
Type of graph for oscillating particles
Displacement- time graphs
Method of creating an oscillation drawing
Pen attached to spring with a mass
Move a piece of white card at constant point
Or
Use motion sensor (transmitter on spring and a receiver)
Phase def
The phase of an oscillation refers to the position within a cycle that the particle occupies in relation to the cycle or other particle
Antiphase
Two oscillations are half a cycle out of step with eachother
Phase difference
The calculated space between two oscillations
360*= (radians)
2 pie
180*
1 pie
90*
Pie/2
270*
3/2 pie
What dies displacement-distance graph show
Shows the phase relationship of masses
Wave profile def
Cross section of the wave at a particular point
Difference between displacement-time and displacement-distance graphs
1) represents the position of all the particles along the sections of the wave as opposed to
2) showing the motion of a single particle within the wave
Degrees to radians calc
Pie/180 x angle in degrees
Radians to degrees calc
180/pie x angle in radians
Wavelength def
Distance between two adjacent points in phase
Electromagnetic waves are created
When charged particles are accelerated
What continuously varies in an electromagnetic wave
Electric and magnetic fields
Have sand frequency as the oscillator
Magnetic field for electromagnetic wave
Is in the vertical
At right angles to the electric field oscillation
Electric field oscillation for electromagnetic wave
In the horizontal
Right angles to the magnetic field oscillation
Electric or magnetic fields do not require
A material medium
Electrical or magnetic fields cannot exist without
Eachother
Anagram for electromagnetic field
Red (radio) Mints (microwave) In (infrared) Violet (visible light) Underpants (ultraviolet) X-ray Grapes (gamma)
Radio or gamma?
Shortest wavelength
Gamma
Gamma ray uses
In medicine to destroy tumours
To sterilise instruments
(Highly penetrating rays)
X-ray uses
More controllable than gamma
Used in medicine for diagnosis and treatment
Can detect faults in materials and metals and crystals
Ultraviolet uses
Stimulates vitamin D in skin creating tan
Makes materials fluorescent
Used in lamps etc
Visible light uses
Focused on eye retina creates image in brain
Photographic film
Energy source for plant photosynthesis
Infrared uses
Radiated by warm bodies
Used for heating and cooking
Also in thermal imaging devices
Microwave uses
Energy transferred to water molecules in food by resonance of microwave frequencies
Used in mobile phones and satellite communications
Radio uses
Wide range of frequencies allow many signals to be transmitted
Telescopes can detect faint sources in space
Speed of travelling wave depends on (2)
- nature of wave
- medium it is travelling through
Wave speed equation
Speed = wavelength / time period (to complete one cycle)
Wave equation
Wave speed = frequency x wavelength
