Flashcards in Chapter 2 - Waves And The Electromagnetic Spectrum Deck (17):
What happens to the particles when a wave passes through them?
They vibrate and transfer energy and information between each other but overall they stay in the same place
What is the amplitude of a wave?
The displacement front the equilibrium (rest position, middle)
What is the wave length of a wave?
The length of a full cycle of the wave (crest - crest or compression - compression)
What is the frequency of a wave?
The number of complete cycles of the wave passing a certain point per second. Measure in hertz (Hz). 1Hz=1 wave per second
What is the period of a wave?
The number of seconds it takes for one full cycle.
Period = 1/frequency
Which direction do transverse waves travel in? Give some examples of waves which are transverse
They travel perpendicular to the direction of the wave (they’re the ones which go up and down).
Most waves are transverse including all EM waves, S-waves, water waves
Which direction do longitudinal waves travel in? Give some examples of waves which are longitudinal
They travel parallel to the direction of the wave. They compress and rarefract the the arrangement of the particles in the medium.
Sound waves and P-waves
What is the formula for wave speed?
Wave speed = Frequency X Wave length
m/s = Hz X m
Wave speed = Distance/Time
m/s = m/s
What are the four types of wave behavior at boundaries
Absorbed, transmitted, reflected or refracted
What happens when a wave is absorbed?
The wave transfers energy to the material’s energy stores. Often the energy is transmitted to a thermal energy store, which leads to heating
What happens when a wave is transmitted?
The wave carries on traveling through the new material. This often leads too refraction
What happens when a wave is reflected?
The incoming ray is bounced back
Explain what refraction is and how it works
Waves travel at different speeds in different density materials. If the wave hits the boundary at an angle, this change in speed causes a change in direction - refraction. If it travels along the normal, it will change speed but not refract. The greater the change in speed, the more the wave will bend.
Which way does a wave bend if it is decelerating? Accelerating?
Decelerating=towards the normal
Accelerating=away from the normal
What is it called when waves separate? How does this happen? Give an example
How much an EM wave refracts depends on its wavelength - shorter wavelengths bend more. E.g. white light dies erasing into a spectrum.
What happens to the frequency of a wave when it enters a new medium? Why is this?
It stays the same. The change in speed is cause by a change in wavelength. As the wavelength decreases, the wave slows down