Wave Flashcards
What is a wave?
Propagation of oscillation in a mediuum.
What kind of wave is sound?
Mechanical wave.
What is a wavelength and what is the base unit?
The distance between two points that are in the same phase (m).
What is velocity of propagation?
Velocity: distance covered by one period (T) : c = lambda/T = Lambda * 1/T = lambda * frequency
Is frequency constant or does it change?
It is constant.
What does the velocity of propagation and wavelength depend on?
The properties of the medium, as the frequency is constant.
It is true for all kinds of waves.
Give an example of a transverse wave. Can it be polarized?
Electromagnetic waves (light). Yes, as it is a transverse wave.
Give an example of a longitudinal wave.
Sound.
What is refraction?
The change in the direction of propagation, when passing through an interface between two media.
The relationship between the angles before and after the interface (incident angle and angle of refraction).
What is interference?
What is the requirement?
When two or more waves meet.
The requirement is that the waves have identical wavelengths and their phase diffeerence stays constant in time.
What is a standing wave?
What is the formula?
What happens if the length is shorter?
The pattern of intereference between plane waves that propagate against each other and have identical wavelengths and amplitudes.
The distance between the two notdes equals half the length.
L= k * lambda/2. (K =1,2,3). If the length is shorter, the lambda will be shorter as well and the frequency increases as the velocity of propagation is constant.
Why does pitch of sound increase if we make it the guitar string shorter?
If the length is shorter, then the wavelength will be shorter as well. Thus the frequency (which determines the pitch) increases because the product of wavelength and frequency is constant.
What is diffraction?
The change in the direction of wave propagating due to an obstacle or slit in the path of the wave (not an interface!)
The smaller the size of the obstacle/slit, the greater the effect of diffraction will be.
What is the Huygens-Fresnel principle?
Concept of wave propagation. According ot this model, every point on a wavefront acts as a source fo new elementary waves.
What is sound?
What is the range of audible sound?
A sound is a mechanical vibration that propagates as a wave in compressible materials.
Audible sound: 20-20 000 Hz.