Oil and water do not mix. Water molecules attract each other and the oil molecules stick together causing the oil and water to form two separate layers. Water molecules sink to the bottom as they are packed close together leaving the oil molecules at the top. The water is heavier than the oil. Liquids are made up of different numbers of atoms and molecules. In some liquids, these atoms and molecules are packed together more tightly, resulting in a denser or heavier liquid. Oil and water are different densities because of this they do not mix instead creating the movement of the two separate liquids within the test tube to produce the illusion of waves.

Water is able to move in many ways. Using the wick the water moves via capillary action, this is how you notice the empty containers start to fill. The water moves via the tiny gaps in the paper towel fibres. Capillary action is the ability of a liquid to flow upward, against gravity, in narrow spaces. The same principle is used to help water climb from a plant’s roots to the leaves. Paper towel is made from fibres found in plants called cellulose. The water flowed upwards through the tiny gaps between the cellulose fibres in this activity.

These gaps in the towel act like capillary tubes, pulling the water upwards. Water is able to defy gravity as it travels upwards due to the force of attraction between the water and cellulose fibres. Using the process of adhesion the water molecules cling to the cellulose fibres of the paper towel. Cohesion is responsible for the water molecules attracting to each other meaning as the water moves up the tiny gaps in the paper towel fibres the cohesion forces help to draw more water upwards. Adhesive forces between the water and cellulose plus the cohesive forces between the water molecules will be overcome by the gravitational forces on the weight of the water in the paper towel. When this happens, the water will not travel up the paper towel anymore.

This activity demonstrates a concept called refraction which is the bending of light. As your arrows are moved to a distance behind the container it gives the appearance they are reversed. When the light passes from one material to another it bends or refracts. Light travels from the air, through the container, through the water, back through the container then back through the air. When light passes from one medium/material into another it refracts. This however does not fully explain why the arrows reverse, this is explained by thinking of the water in the container as a magnifying glass.

As light passes through a magnifying glass it bends towards the centre. The focal point is when the light all comes together but beyond the focal point any images appears to reverse because the light rays that were bent pass each other and the light that was on the right side is now on the left and the left on the right making the arrows to appear in reserve.

Surface tension is the way water collects around a rounded surface. It’s this that creates the domed look of the water on the penny. Water has a strong surface tension because of its polarity. Water molecules are polar, this means one end of the water molecule has a positive charge and the other end has a negative charge.

Opposites attract meaning the water molecules are attracted to one another forming hydrogen bonds. Soap decreases the surface tension of the water causing the water molecules to push apart. The hydrophobic ends of the soap molecules (they do not want to be near water) squeeze between the water molecules as they work towards the surface resulting in less water collecting on the penny.

Red, blue and yellow are primary colours of light. When you combine these colours in equal amounts white light is produced. When they are combined in different amounts
they produce other colours called secondary colours. In this activity primary colours blue and yellow are used combining to make the secondary colour green.