![]() The areas where the coils are closer together, we call Compressions the areas where the coils are further apart, we call Rarefactions. Very quickly you will see a pattern develop in the spring coils where some of the coils are closer together than normal and others are further apart than normal. To demonstrate a Longitudinal type of wave using a slinky, keep one end fixed and vibrate the other end to and fro (forward and backward) A slinky is a long spring which when stretched out, looks a bit like this: The best way to picture such a wave is to use a "slinky". If the vibration is Longitudinal to the direction of the wave eg to and fro (forward and backward) along the direction of the wave, then the resulting wave.is harder to picture !.Interestingly, ALL of the electromagnetic waves, listed in the table above, are of the Transverse type because they are all caused by vibrating electric and magnetic fields which both vibrate transverse to the direction of the wave, as shown below. (NB Sometimes the "thing" that vibrates is called a "disturbance" dropping a stone into water is an obvious example of a "disturbance" moving the rope up and down is a "disturbance".) The dropped stone merely drops into the water, doesn't it the hand moving up and down in the water doesn't travel along with the resulting ripple, does it? Notice - the "thing" that vibrates or which causes the disturbance does not travel along the wave. You will see a transverse wave on the rope and if you vibrate it faster and faster you will see more and more distinct waves along the length of the rope. You will have made a water wave.Īnother way to make a water wave is to drop a stone into some water and the downward movement of the stone sets up a ripple across the surface of the water.Īnother simple way to demonstrate a Transverse wave is to get a skipping rope or any long rope, keep one end still, then vibrate the other end up and down. Notice the repeating pattern of peaks and troughs (maximums and minimums) this is a characteristic of a Transverse wave.Ī good example of how you can make a wave like this is - in a swimming pool, push your hand down into the water, then raise it to the surface, then repeat etc you will see a "ripple" moving away from you. If the vibration is Transverse to the direction of the wave eg Up and Down or Side to Side, then the resulting wave will look like this:.What do these two types of wave look like? The following simple diagrams should make the distinction clear. If the "thing" vibrates a long (or, in line with) the direction of travel of the wave then the wave is of the Longitudinal type. If the "thing" vibrates transverse to (which means, at right angles to) the direction of travel of the wave then the wave is of the Transverse type. The "thing" that vibrates can be a mechanical thing such as a particle (eg water particle) or an electromagnetic thing such as an electric/magnetic field. When we categorise waves into these 2 categories we are focussing on how they travel rather than on what they consist of.Īll waves travel by means of some vibration. The second way that we categorise waves is to put them under the headings Transverse Waves or Longitudinal Waves. Electromagnetic waves, on the other hand don't need anything mechanical to travel through they can travel through a vacuum eg the light from the sun and stars travels easily in space. Mechanical waves have to travel through some mechanical or physical medium such as air/gas or water/liquid or ground/solid, because they travel by making the mechanical medium vibrate. So is a sound wave in air because it consists of vibrating air particles mechanical stuff.īut a visible light wave does not consist of anything mechanical it consists of vibrating electric and magnetic fields, so what type of wave is it? Its an electro - magnetic wave. When we categorise them under these headings we are focussing on what they are or what they consist of.įor example, a water wave consists of vibrating water particles mechanical stuff, so a water wave is a mechanical wave. We can put them under the headings Mechanical Waves or Electromagnetic Waves. The first way is the easiest but is very important to understand before encountering the second way.ġ. ![]()
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