Achange in the direction of a wave when the wave finds an obstacle or an edge, such as an opening bending of waves around a barrier is called question 3 options: refraction diffraction crest trough

A change in the direction of a wave when the wave finds and obstacle or an edge, such as an opening, bending waves around a barrier is called *diffraction*.

Diffraction. Can be seen in a school "ripple tank experiment". Plane/straight water waves approach an obstacle. At the edges of the obstacle, the waves will be seen to "bend" or to "spread" into what "should" be the shadow of the obstacle. Same thing happens with all waves going to barriers with the correct geometry. 

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