Sagot :
they are slowed down.
even air is a medium and will slow down waves (slightly) compared to a vacuum/ space
if the wave hits the medium at an angle it can be 'bent' (refracted) like light through a glass prism
even air is a medium and will slow down waves (slightly) compared to a vacuum/ space
if the wave hits the medium at an angle it can be 'bent' (refracted) like light through a glass prism