P6 Flashcards
Describe how energy is transferred in waves
When waves travel through a medium, the particles of the medium oscillate and transfer energy between each other
What direction the waves transfer energy
Direction they are travelling
What is the amplitude of a wave
The maximum displacement of a point on the wave from its undisturbed position
What is the wavelength of the wave
Distance between the same point onto adjacent waves
What is the frequency of a wave, What is it measured in and what is one of these equal to
The number of complete waves passing a certain points per seconds, hertz, one wave Per second
Is the period of a wave and how do you work it out
The amount of time it takes for a full cycle of the wave to pass a points – one over frequency
What are the two types of waves
Transverse and longitudinal
Describe the oscillations in transverse waves
Perpendicular to the direction of energy transfer
What are examples of transverse waves
All electromagnetic waves e.g. light
– ripples and waves in water
– a wave on a string
Describe the oscillations in longitudinal waves
– Parallel to the direction of energy transfer
What is a key characteristic of longitudinal waves
Rarefractions and compressions
What are examples of longitudinal waves
– Soundwaves in air, ultrasounds
– shockwaves e.g. some seismic waves
What is the equation for wave speed in metres per second
Frequency times wavelength in metres
How could you measure the speed of sound
– Attach a signal generator to the speaker – generate sounds with a specific frequency
– used to microphones and an oscilloscope to find wavelength of the sound waves generated
Describe the method of measuring the speed of sound
– Set up oscilloscope so the detected waves at each microphone shown as separate waves
Starts with both microphones next to the speaker, then slowly move on away until the two waves are aligned on the display but have moved exactly one wavelength apart
– measure the distance between the microphones to find out one wavelength
– use the formula to wave speed to find the speed of the sound waves passing through air – frequency is whatever you set the signal generate two – around one kHz
What is the speed of sound is roughly
330 m/s
Describe the equipment for the practical of measuring the speed of water ripples
– Strobe light over water placed in tree over screen
– signal generator attached to dipper – water waves at set frequency
Describe the method of the wave water speed practical
– Dim lights and turn on strobe lights – sea wave pattern made by shadows of Wavecrest sunscreen blowtank
– increased frequency of strobe light until the wave pattern on the screen appears to freeze and stop moving – happens when the frequency of the strobe light is equal to the frequency of the waves
– distance between each shadow and line is equal to one wavelength – measure distance between shadow lines that are 10 wavelengths of parts then divide this distance by 10 defined average wavelength – suitable for measuring small wavelengths
Why is the strobe a suitable piece of equipment in the wave water speeds practical
It allows you to measure a steel pattern instead of a constantly moving one
Describe the equipment for the wave and string experiment
– Attach signal generator to vibration transducer which is attached to string and a pulley on a bench with masses hanging off the end using a clamp and hook
Describe the methods of the wave string practical
– I just frequency setting on the signal generator to change length of we’ve created on string
– keep adjusting the frequency of the signal generator until there appears to be a clear wave- standing wave from resonance
– measure the length of all the half wavelengths on stream in one go then divided by the total number of half wavelengths to get them in half wavelength
– double the value to get a Photo wall wavelength
– frequency of a wave it’s whatever the signal generator is set to
– find speed of a wave by times in the frequency by the wavelength
When in the string wave practical there appear to be one clear wave
When a whole number of half wavelengths fit exactly on the string – if you want at least four or five ideally
What does the frequency you need in a string wave practical depends on
The length of string between the pulley and transducer and the masses you have used
What type are all electromagnetic (EM) waves, what do they do and what are they
– Transverse
– transfer energy from a source to an absorber