4. Waves Flashcards
Define displacement
Distance of an oscillating particle from its equilibrium position in a specified direction
Define amplitude
The maximum displacement of an oscillating particle from its equilibrium position
Define wavelength
The distance between any 2 successive points in phase
Define period
Time taken for a particle to undergo 1 complete cycle of oscillation
Define frequency
No. of complete cycles of a particle per unit time
Define wave speed
Distance the wave profile moves per unit time
Define transverse waves
Waves in which the displacement of the particles of the medium is perpendicular to the direction of the wave motion
Define longitudinal waves
Waves in which the displacement of the particles of the medium is parallel to the direction of the wave motion
What are electromagnetic waves?
2 sinusoidal fields (E & B field), oscillating in phase and perpendicular to each other
State all electromagnetic waves, in ascending order of wavelength
Gamma rays, X-rays, ultra-violet radiation, visible light, infra-red, microwaves, radio waves
Wavelength of gamma rays
10^-14
Wavelength of X-rays
10^-10
Wavelength of ultra-violet radiation
10^-8
Wavelength of visible light
10^-7
Wavelength of infrared radiation
10^-5
Wavelength of microwaves
10^-2
Wavelength of radio waves
10^1
Define wavefront
A line joining the points of a wave that are in phase
Define ray
The path taken by the wave
Define intensity
The rate of energy flow per unit cross sectional area perpendicular to the direction of wave propagation
Power/Area
How is intensity related to amplitude and radius?
Proportional to the square of amplitude
Proportional to 1/r^2
State the principle of superposition
When 2 or more waves of the same kind exist simultaneously at a point in a medium, the resultant displacement of waves at a given point in time and space is the vector sum of the displacement due to each wave acting independently.
What is the polarisation of light?
When its electric fields oscillate in a single plane, rather than any direction perpendicular to the direction of propagation