Waves Flashcards
What is are waves (wave motion)?
Wave motion is the transmission of energy from one place to another through a material or vacuum
What is a progressive wave?
A progressive wave a travelling wave consist of a disturbance moving from a source to the surrounding places, as a result of which energy is transferred from one point to another.
What are the two types of waves?
Longitudinal and transverse waves
What is a longitudinal wave?
A wave is said to be longitudinal wave if the displacement of mechanical particles is parallel to the direction or translation of energy such as a sound wave
What is a transverse wave?
A wave is said to be a transverse wave if the wave has associated with some vector displacement which is parallel to the direction or translation of energy
What is the wave displacement?
Distance a point on the wave from it’s undisturbed position or equilibrium position is called displacement
What is the amplitude?
The maximum displacement of any point on the wave from its undisturbed position is called amplitude
What is the wavelength?
The distance from any point on the way to the next exactly similar point.
What is the frequency?
The number of oscillations per unit time of a point in a wave is called frequency
F=1/T
T= time period
What is the mechanical waves?
Waves are called mechanical waves if we need a substance or medium to travel through
What is a phase difference and what is it measured in?
When one point on a wave vibrates the point next to it vibrate sslightly out of step with it we say that the vibrate out of phase with each other - there is a phase difference between them. this is the amount by which one oscillation leads and lags behind. Phase difference is measured in degrees
How is energy transferred in waves?
The particles that make up the material through which the wave is travelling do not move along they only oscillate about a fixed point. It is energy that is transmitted by the wave each particle vibrates as it does so pushes its neighbour transferring energy to it than that particle pushes its neighbour which pushes its neighbour in this way the transferred from one particle to the next
What is intensity? Unit?
the intensity of a wave is defined as the rate of energy transmitted per unit area at right angles to the wave velocity. Intensity is measured in watts per square metre.
Intensity=Power/cross-sectional area
Why does the intensity of the wave decrease as it travels?
Number 1; the wave may spread out or Number 2; the wave may be absorbed or scattered
What is the relationship of amplitude and intensity?
Intensity is directly proportional to the square of amplitude
What is wave speed, what are its units and what is the wave equation ?
The speed with which energy is transmitted by a wave is known as wave speed this is measured in metres per second.
Wave speed= frequency X wave length
What is the speed of sound?
330 m/s
What sound frequencies can humans detect
From 20hz to 20khz
What is The Doppler Effect
The pitch of an object that is emiting waves (light or sound) is higher as it approaches you and lower as it recedes into the distance
How does the doppler at work?
As the object Moves the waves in the direction in which the object is moving will squeeze together thus have a higher frequency then the frequency of the source and a shorter wavelength on the other hand the Waves on the opposite direction will be more further apart and stretched out which means that they will observe a lower frequency and higher wavelength
What is the formula for observed frequency in the dopplers effect
When object Moves towards observer:
Observed frequency= frequency of sourcevelocity/(velocity-velocity of source)
When object moves from away from observer:
Observed frequency= frequency of sourcevelocity/(velocity+velocity of source)
What are some important points of Doppler effect in waves
- The frequency of the source is not affected by the movement of the source
- the speed of the wave as they travel through the air is also affected by the movement of the source
