Wave experiments Flashcards
What can you use to measure the speed of sound?
An oscilloscope
By attaching a signal generator to a speaker you can generate sounds with a specific frequency.
What equipment can you use to find the wavelength of the sound waves generated?
Two microphones and an oscilloscope
Zara is using two microphones and an oscilloscope to find the wavelength of the sound waves.
How do you set up the experiment with the equipment to find the wavelength of sound waves generated?
1) Set up the oscilloscope so the detected waves at each microphone are shown as separate waves.
2) Start with both microphones next to the speaker , then slowly move one away until the next two waves are aligned on the display, but have moved exactly one wavelength apart.
3) Measure the distance between the microphones to find one wavelength.
4) You can then use the formula wave speed = frequency x wavelength to find the speed of the sound waves passing through the air - the frequency is whatever you set the signal generator to in the first place.
What piece of equipment can you use to measure speed, frequency and wavelength?
A ripple tank
How do you measure the frequency of a wave in a ripple tank?
1) Float a cork in the ripple tank. It should bob up and down as the waves pass it.
2) When the cork is at the top of a ‘bob’ start the stopwatch. Time how long the cork takes to complete 10 bobs.
3) Divide this time by 10 to get the time for one bob - the period
4) Calculate the frequency using the formula: frequency = 1/period
How do you measure the wavelength of a wave in a ripple tank?
1) Place a card covered with centimetre-squared paper behind the ripple tank.
2) Turn on the strobe light and adjust its frequency until the waves appear to ‘freeze’.
3) Using the squared paper, measure the distance that, e.g. five waves cover. Divide this distance by the number of waves to get an average wavelength
How do you measure the wave speed of a wave in a ripple tank?
1) Place a large piece of paper next to the tank.
2) As the waves move across the tank, one of you should track the path of one of the crests on the paper using the pencil. Using a ruler will help make sure your line is parallel to the direction the wave travels.
3) The other should time how long it takes the first to draw a line of a certain length, e.g. 20cm.
4) Calculate wave speed by plugging the length of the line (distance) and the time taken to draw it into the formula: speed = distance/time
How many repeats should you do for wave experiments?
3 repeats
