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Wave related experiments

Waves are really useful, you can do a lot with them. Their used in telephones and electronics, the modern age is what it is in part to our understanding of waves. Bellow are some basic experiments that allow us to observe the properties of waves.

1. The Speed of Sound

Sound is the transference of vibrational energy through collisions between neighbouring molecules. In air we know the speed of sound to be 330ms-1. We can prove this using:

• Tape measure
• Signal generator
• Microphones
• Oscilloscope

Then set up as shown below:

a) Using the frequency generator choose a frequency and play it through a connected speaker.

b) Using microphones connected to an oscilloscope we can observe the wave produced on screen. Moving the second microphone from the first one find the next point along the sound wave where the wave repeats in sync.

c) Measure the distance between microphones, it’s the wavelength of the wave 𝜆.

d) Using 𝑓𝑥𝜆 = 𝑣 we can calculate the speed of sound in air.

2. Speed of Water ripples

Water ripples are a lot easier to measure the speed of it can be done with some low-tech equipment. You will need:

• Wave generator
• See through water tray
• Lamp
• Camera
• Stopwatch
• Ruler

Then set up like so:

You’d set up a water tray with a wave generator at one end and place a lamp over it and a ruler underneath. Once the wave

generator is turned on you’ll see the waves rippling across. These ripples will cast a shadow onto the surface bellow the tray, now using a camera or stop watch we can figure out how long it takes a wave to travel a given distance. Then using the time taken and distance we can calculate the waves velocity, since velocity = distance/time.

Take note both of the experiments above deal with longitudinal waves. As a result, when moving from one medium to another the wave speeds will change. These waves will travel faster when entering a denser medium.

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