P6 - Waves Flashcards
What can waves be?
Transverse or longitudinal
Example of a transverse wave
The ripples on a water surface - it is the wave that travels and not the water
What do longitudinal waves show
Compression and rarefaction
Examples of a longitudinal wave
Sound waves travelling through air - it is the wave that travels and not the air itself
What is the difference between transverse and longitudinal waves (3)
- In transverse waves the oscillations (vibrations) are perpendicular (at 90°) to the direction of energy
- Where as in longitudinal waves, the oscillations are parallel to the direction of energy transfer
What is the amplitude of a wave
Is the maximum displacement of a point on a wave away from its undisturbed position
What is the wavelength of a wave
Is the distance from a point on one wave to the equivalent point on the adjacent wave
What is the frequency of a wave
Is the number of waves passing a point each second
Equation for period
Period(s) = 1/frequency (Hz)
Equation for frequency
Frequency = 1/period (s)
What is wave speed
Is the speed at which the energy is transferred (or the wave moves) through the medium
The wave equation that all waves obey
Wave speed (m/s) = frequency (Hz) x wavelength (m)
Wave diagram
Check photos
Describe a method to measure the speed of sound waves (3)
- set up an oscilloscope so the detected waves at each microphone are shown as separate waves
- start with both mics next to the speaker, then slowly move away until the two waves are aligned on the display, but have moved exactly one wavelength apart
- Measure wavelength - then use the wave speed formula
Measure the frequency, wavelength and speed of waves in a ripple tank - required practical (apparatus) (5)
- Lamp
- Dipper
- Water
- Signal generator
- Metre ruler
Measure the frequency, wavelength and speed of waves in a ripple tank - required practical (method) (4)
- Using a signal generator attached to the dipper of a ripple tank you an create water waves at a set frequency
- Dim the lights and turn on lamp - should see wave crests as shadows on the screen below
- The distance between each line is the wavelength - find the average wavelength after 10 lines
- Use the equation wave speed = wavelength x frequency
Measure the frequency, wavelength and speed of waves in a solid - required practical (apparatus) (6)
- Vibration transducer
- String
- Pulley
- Signal generator
- Bench
- Masses
Measure the frequency, wavelength and speed of waves in a solid - required practical (method) (4)
- Adjust the frequency of the signal generator until there’s a clear wave on the string - frequency will depend on the length of string between the pulley and the transducer, and the masses you’ve used
- the best way to measure the wavelength is to measure lengths of 4 or 5 half wavelengths in one go then get an average then double to get a full wavelength
- The frequency is whatever the signal generator is set to
- You can find the speed using the wave speed = wavelength x frequency equation
Electromagnetic waves (3)
- Are transverse waves that transfer energy from the source of the waves to an absorber
- Form a continuous spectrum
- All types of electromagnetic wave travel at the same velocity through a vacuum or air
How are the waves that form the electromagnetic spectrum grouped
In terms of their wavelength and their frequency - going from long to short wavelength or from low to high frequency
Groups in the electromagnetic spectrum (7)
Radio waves, microwaves, infrared, visible light, ultraviolet, x-rays, gamma rays
What do our eyes only detect
Visible light - so detect a limited range of electromagnetic waves
Example of transfer of energy by electromagnetic waves (camp fire)
- A camp fire transfers energy to its surroundings by emitting infrared radiation
- These infrared waves are absorbed by objects and transfer energy to the object’s thermal energy store, causing the object to warm up
Example of transfer of energy by electromagnetic waves (radio waves)
Radio waves transfer energy to the kinetic energy store of electrons in radio receivers, which generates