Week 5 Flashcards
Doppler Effect
Change in frequency of sound or light due to the motion of the source or receiver
Sound
A longitudinal wave that consists of compressions and rare-fractions of the medium
Reflection
Return of light rays from the surface in such a way that the angle at which the given ray is returned is equal to the angle at which it strikes the surface.
Rarefraction
Bending of an oblique ray of light when it passes from one transparent medium to another, caused by difference in speed.
Natural frequency
Frequency at which an elastic object tends to vibrate if it is disturbed and then the disturbing force is removed.
Resonance
Frequency of forced vibrations on an object matches the object’s natural frequency, producing a dramatic increase in amplitude.
Explain how the frequency and wavelength of a periodic disturbance are altered if the source of the disturbance is moving.
The Doppler Effect
Outline the Doppler Effect
The sound varies in pitch depending on where the receiver is moving in relation to the source. The sound varies depending on whether the source is moving towards or away from the receiver.
Explain how the magnitude and direction of frequency change of the Doppler effect indicates the
direction and speed of the moving wave source
The higher the change or direction in frequency change, the faster the source is moving, if the pitch is higher then the source is moving towards the receiver.
Explain how, for sound waves, the Doppler effect holds if either the sender or receiver of the sound
waves is moving;
*The ambulance example from Assignment 2.
The relationship between the direction the source/receiver is moving towards/away from the receiver/source changes the interpretation of the sound.
Explain why sound can be described as a pressure wave;
Sound can be described as a pressure wave as it has compressions (high pressure) and rarefraction (low pressure) areas.
Explain how sound is propagated and moved through a medium
Sound is propagated by high and low pressure areas,
Explain what determines the frequency of a sound wave that is emitted from a source
The frequency is determined by how fast the source is vibrating.
Relate the velocity of sound in a medium to the density and stiffness of the medium
The denser the material, the faster the sound would travel through the material. This is because the atoms are closer together and therefore the sound travels quicker.
Outline the process of sound absorption
Acoustic absorption refers to the process by which a material, structure, or object takes in sound energy when sound waves are encountered, as opposed to reflecting the energy. Part of the absorbed energy is transformed into heat and part is transmitted through the absorbing body.
