Respuesta :
					                   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
 
			                  