Waves Flashcards
What is frequency? (Give unit)
- The number of waves passing a point each second
- Measured in hertz (Hz)
What is a period?
The time taken for one wavelength to pass a point
1 / Frequency
Are seismic P waves transverse or longitudinal?
Longitudinal
Are seismic S waves transverse or longitudinal?
Transverse
Are sound waves transverse or longitudinal?
Longitudinal
Are electromagnetic waves transverse or longitudinal?
Transverse
What are the equations for wave speed?
Wave speed = Frequency x Wavelength
Or
Wave speed = Distance / Time
When a wave enters a less dense medium will it refract towards or away from the normal?
Away from the normal
How do you calculate the speed of sound in air using an echo?
- Measure distance from the source of sound to reflecting surface (wall)
- Measure the time interval, with a stopwatch, between original sound being produced and echo being heard
- Use (speed = distance/time) to calculate the speed
How do you calculate the speed of sound in air using two microphones and an oscilloscope?
- Set up the microphones, one in front of the other, at different distances in a straight line from a speaker
- Set the frequency of the speaker sound to unknown, audible value
- Display the two waveforms on the oscilloscope
- Measure distance between microphones
- Move the microphones apart so the wave forms move apart by one wavelength
- Calculate the speed of sound using (wave speed = frequency x wavelength)
How do you calculate the speed of ripples on water surfaces?
- Set up a ripple tank
- Switch on lamp and motor and adjust until low frequency waves can clearly be observed
- Measure the length of a number of waves then divided by the number of waves to record wavelength
- Count the number of waves passing a point in 10 seconds then divide by 10 to record frequency
- Calculate the speed of waves using (wave speed = frequency x wavelength)
How does the amplitude of a soundwave affect the volume of the sound?
High amplitude - sound waves are loud
Low amplitude- sound waves are quiet
What are some uses of ultrasound?
- Breaking kidney stones
- Cleaning jewellery
- Foetal scanning
- Detecting cracks in machinery
- Sonar
How do ultrasounds work?
- Ultrasound waves are sent into the woman’s body
- Some of the sound is reflected each time it meets a layer of tissue with a different density
- The scanner detects the echoes and the computer uses the information to make a picture
What are the uses of infrasound?
- Infrasound is produced when meteors enter the earths atmosphere, scientist track the path the meteor will take
- Can help determine the structure of rocks beneath the earths crust
