Physics - Waves Flashcards
Radio waves
Electrons vibrate sending out EM waves that make different electrons vibrate at the same frequency in receiving antenna ; transferring energy (no electrons are transferred)
Waves transfer
Energy and not matter
Transverse
Vibration direction is perpendicular to the wave direction
Longitudinal waves
Vibration direction is parallel to wave direction
Transverse waves
EM waves
Waves on a string
Seismic S-waves
Longitudinal
Sound
Ultrasound
Compression waves on a slinky
Seismic P-waves
Water waves
Mixture of transverse and longitudinal waves so particles of water move vertically and horizontally as the wave passes
Compression
Longitudinal - particles are pushed closer as wave passes
Rarefaction
Particles in medium are pulled further apart as wave passes
Compressions
Higher pressure than atmospheric
Rarefactions
Lower pressure than atmospheric
Frequency formula
1/time taken for one cycle (Hz)
Mechanical waves
Vibrating particles so they can only move through a material medium ; cannot travel through a vacuum
EM waves
No material medium needed ; can travel through vacuum
EM waves
Speed of light
EM spectrum
Radio, micro, infra-red, visible, uv, x-ray, gamma rays
Gamma
Short wavelength
High frequency
Mechanical waves
Ultrasound /seismic waves/water waves
Nature of EM waves
Charged particles, electrons, set up an electric field in the space around them ; magnetic field also produced when they vibrate and this pattern of electric field and magnetic field travels outwards as an EM wave
Wavelength
Distance between adjacent peaks or compressions (longitudinal)
Amplitude
Maximum displacement from equilibrium
Period
Time taken for one vibration
Frequency
Number of oscillations per unit time
Frequency
Number of cycles/second
