Which seismic wave refracts and cannot penetrate the core

P waves and S waves travel through the interior of the earth. P waves are the Primary waves and S waves are the Secondary waves.

    P waves can travel in both solid as well as in liquid (outer core) whereas S wave can travel only through solid. When P waves enters the outer core, it gets deviated and again enters the outer core with further deviation.

               In case of S waves, once it reaches the core-mantle boundary, it reflects to the side of it, forming a shadow zone commonly known as the S wave shadow zone (103°-103°). Thus it cannot penetrate through the outer core.

in chemistry, adhesion and cohesion are attractive forces that exist between molecules. they hold the molecules together from each other. they are different in that adhesive force exists between molecules of different substance while cohesive force happens between molecules of same substance.

adhesion between water and glass causes water molecules at the edge of water and glass interface to climb up the wall in a narrow glass tube. this is called capillary action. cohesion is what gives glass its shape and causes water to form a droplet.