Waves Flashcards
Number of oscillations per unit time
Frequency
Maximum displacement from equilibrium position
Amplitude
Time taken for one complete oscillation
Period
Angle to describe of different stages of oscillatory cycle
Phase difference
Restoring force is proportional to displacement and directed towards equilibrium
SHM
Gradual loss of energy of an oscillator due to resistance forces
Damping
Increase of amplitude when forced to oscillate at natural frequency
Resonance
Wave for which points along the wave is at 90 degrees to direction of energy propagation
Transverse
Displacement is parallel to energy propagation
Longitudinal
A way of transferring energy and momentum
Wave
Can travel in vacuum
Electromagnetic waves
A wave is associated with a … And travels in a medium (can be vacuum)
Disturbance
Speed of .. Determined by properties of the medium (tension and mass per unit length) and not how the wave is created.
Wave pulse
Created if one pulse after another is created
Travelling wave
Wave moves forward a distance equal to
Wavelength
Surface through crests and normal to the direction of propagation of the wave
Wavefront
Lines in the direction of propagation of the wave
Rays
Rays are radial lines on … Wavefronts
Cylindrical
The displacement at a point is the algebraic sum of the individual displacements
Superposition
Pulse changes in direction and is inverted when
Reflected
The angle of incidence is equal to the angle of…
Reflection
Relates the sines of the angles of incidence and refraction to the speed of the wave in the two media
Snells law
Applicable to light only, n1sinx1=n2sinx2
Index of refraction
Angles of the same angles of incidence but different wavelengths are refracted by different angles
Dispersion
Spreading of a wave as it goes past an obstacle or through an aperture
Diffraction
In diffraction; if aperture is very small, as if only one point in the wavefront will act as a source of waves, these will be circular, and the wave will spread
Huygens principle
Many points on the wavefront will act as sources of secondary waves and these will tend to be planar
If the aperture is large
Result of superposition of two waves. Demonstrated by Young
Interference
If path difference is an integral multiple of the period of the wave
Constructive interference
If path difference is a half integral multiple of the period; waves cancel out and are observed as zero wave
Destructive interference
Change in frequency of wave received by an observer compared to the frequency with which it was emitted
Doppler effect
When two waves of the same speed, wavelength and amplitude travelling in opposite directions meet, … Is formed
Standing wave
Difference between travelling and standing wave
No momentum is transferred
Standing wave with both ends fixed; wavelength = 2L
Fundamental
When both ends are fixed, wavelengths satisfy
2L / n
When one end is fixed and the other is free,
Wavelength = 4L / n
Both ends are free, wavelength
2L / n
