Read the note at the end of the lesson. Students observe the effect of light refraction on a straw protruding into the air from a glass of water. When an object is seen in water, the light rays are bent as they travel through the air into the water. This causes the object in the water to appear to be in a different place than it really is. Different liquids cause light to refract to different degrees depending on the density of the liquid Even though water is clear, looking through it changes the way you see things.
Light travels slower through water than through air.
The bending of light is called refraction . When you place a straw partially in water your eyes see light from the end of the straw first. The light travels from the straw through the air to your eyes. The part of the straw in the water reflects light through the water into the air, then to your eyes. Try placing a teaspoon in a glass half full of water.