Definitions Flashcards
Define transverse wave
A wave which has oscillations perpendicular to the direction of energy transfer.
Define longitudinal wave.
A wave which has oscillations parallel to the direction of energy transfer.
Define progressive wave.
A wave which oscillates through space (matter or a vacuum) and transfers energy but not matter.
Define stationary wave.
A wave that remains in a constant position with no net transfer of energy, created by two progressive waves of the same frequency and amplitude superposing.
Define amplitude.
Maximum displacement from the equilibrium position in the positive or negative direction (metres)
Define wavelength.
The distance between two points in phase on adjacent waves. The length of one complete wave (metres).
Define frequency.
The number of wavelengths passing a given point per unit time (Hertz).
Define period of oscillation.
The time taken for one whole wavelength to pass a given point= 1/frequency. (seconds)
Define wave speed.
The distance travelled by a wave per unit time (ms^-1)
Define phase difference.
The difference between displacements of particles along a wave/on different waves (degrees or radians).
Define coherent.
Two waves with a constant phase difference between them.
Define superposition.
The overlap of two waves at a point in space.
Define interference.
The superposition of two progressive waves from two coherent sources.
Define constructive interference.
Superposition of two waves in phase, so that the resultant wave has a greater amplitude than the original two.
Define destructive interference.
Superposition of two waves in antiphase, so that the waves cancel each other out and the resultant amplitude is smaller than the original waves.
Define path difference.
The difference in the path traversed by two waves
Define node.
A point on a standing wave where the amplitude is 0- caused by the superposing waves interfering destructively.
Define antinode.
A point on a standing wave where the amplitude is at its maximum- caused by the superposing waves constructively interfering.
Define fundamental frequency.
The lowest frequency of a stationary wave.
Define harmonics.
A wave whose frequency is a positive integer multiple of the fundamental frequency of a periodic signal. Fundamental frequency is the 1st harmonic.
Define refraction.
The change in direction or propagation of any wave as a result of it travelling different speeds at different points along the wave front.
Define reflection.
Change in direction of a wavefront at a boundary between two media so that the wavefront returns to the medium from which ir originated.
Define total internal reflection.
Complete reflection of a ray of light from a boundary back into the medium from which it originated. Only occurs if the angle of incidence is greater than the critical angle.
Define diffraction.
Waves spreading out when they travel through a gap or past an obstacle. Does not change the speed, wavelength or frequency.
