3.8 understand that waves can be diffracted when they pass an edge

When a wave meets an obstacle, it could be reflected, refracted or diffracted.

If they are diffracted this just means that the edges of the waves 'bend' to get through gaps, this causes the waves to spread out and allows for waves to travel around corners.

The amount of diffraction depends on the size of the gap relative and the wavelength of the wave, the narrower the gap or the longer the wavelength, the more the wave spreads out

Here's what happens...