Wave+Interactions

=Interference= When two waves travel through the same medium they will be displaced upwards (see diagram) if they both have +1 displacement. As you can see in the diagram when the blue and red waves have the same amplitude and also collide when they are displaced upwards and create a big neutral pulse (known as the green pulse in the diagram). An example may be if two water waves collide exactly shown in the diagram the water will be pushed upward because of the +1 displacement therefore the netrual wave will be pushed upward. There are two types of ways waves that may be interfered with. Constructive waves and Destructive waves. = =

Constructive interference
Constructive interference occurs in a medium when pulses collide head on, meaning they have the same amplitude or same displacement unit. When the two pulses or waves collide in this situation the amplitudes between the two pulses create one larger pulse with the amplitudes of both the pulses. As you can see in the diagram the red and blue pulses both have -1 displacement and the same amplitude.

Destructive interference
Destructive interference occurs when pulses with different displacement units or different amplitudes collide. As you can see in the diagram the red pulse has +1 displacement units and the blue pulse has -1 displacement units. When these two pulses collide they do not destroy each other, they just simply overlap each other.



Two equal waves don't need to have equal or the same amplitudes in opposite directions for a destructive wave to occur. For example one pulse has +1 displacement units and the other has -2 displacement units collide the wave will become a -1 displaced pulse unit. This is still a destructive interference because the two waves have different amplitudes or different displacement numbers.



=Reflection= Reflection is a scientific term that explains a change in the waves direction when bounced off a barrier. A ray will always be reflected when meeting a barrier, even if the ray is on a 90.219 degree turn and the barrier is on a 90.220 degree turn it will always reflect. When a ray or wave has reflected most of its energy has been transferred into the barrier and then loses its wavelength, speed, amplitude etc and will become a low-energy wave.

Law of reflection
The law of reflection explains what occurs when a ray is going to be reflected off a barrier. There are aspects and parts that create this theorem and are:

Angle of incidence: A ray which is travelling in the direction of a barrier and will be reflected on an angle Angle of reflection: A ray which was previously the angle of incidence that has been reflected off a barrier, we can determine the angle of the reflection if we know the angle of incidence. If the angle of incidence is on a 35 degree angle, angled at a mirror, the angle of reflection will reflect at an angle of 35. The normal: Where the angle of incidence collides on a barrier/mirror and reflects, making the angle of reflection Mirror: A medium or substance which is opaque and is able to reflect waves. Mirrors cannot be penetrated by rays unless they are high frequency x-rays and gamma rays



= = =Refraction= Refraction involves an alter when waves change directions if they pass another medium (see diagram). If or when a wave travels through a different medium with different properties it will change wavelength and speed. For example if a person screams, the higher into the air the slower the sound waves speed and wavelength will change.

When a ray is changing mediums, the ray will always change angle. E.g. a rock is dropped into a fish bowl. Humans eyes see always in a straight direction, so when light is refracted in the water, the rock will always be in a different direction then what your eyes see. If you look at both diagrams below, the incident rays direction is the light before it is refracted, if the incident rays line continued into medium 2 as a straight line, that describes how humans see through water if medium 2 was water and medium 1 was air. =Diffraction= Diffraction is when a wave usually changes direction when coming across barriers or open spaces. For an example a water wave is capable of going around obstacles because of its medium. Diffraction mainly occurs when barriers are in the waves way and when open spaces alter the movement or medium of a wave.

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