The Let's Find Out crew bring you three experiments where you won't believe your own eyes! It's all about tricks of the light.

So, let's join the crew of the spaceship curiosity with Captain Zoom, plus scientists Amy and Mark to learn some cool science. It's all made with support from our friends at the Science Foundation Ireland.

Tune in to RTÉjr weekdays at 7am and 2.30pm or watch it any time on RTÉ Player!

Here, after discovering a magnifying glass, Zoom wants to find out more about light. So, Ruby and Mia show her three different "tricks" that they can play with light.

1. The bending straw experiment

You will need:

  • A jug of water
  • A tall glass
  • A straw or pencil

What to do:

  • Place the straw into the glass.
  • Bend down so you are looking at the glass at eye level.
  • Ask someone to pour water into the glass and observe how it looks above the water level, below the water level and at the top of the water level.

The science bit

Did the straw appear to bend at the point where it passed into the water? That is because light bends when it passes from one thing to another, like when it passes from air to water. When we are looking at the straw from the front, light passes through the glass and the water and bounces off the straw, returning to our eyes and that is how we see the straw.

At the top of the glass there is no water so the light passes through glass and air before bouncing off the straw and returning to our eyes.

This difference in how the light bends differently in air and water makes the straw appear bent. It is what we call an optical illusion.

2. The moving arrow experiment

You will need:

  • A jug of water
  • A tall glass
  • Some paper or card
  • A marker

What to do:

  • Using the marker, draw an arrow on the card that points to the left or right.
  • Place the card about 10cm behind the glass of water and prop it up against something so it stays upright; the arrow side of the card facing towards the back of the glass.
  • Bend down so you are looking at the glass of water, from the front, at eye level.
  • Slowly pour water into the glass. Does anything happen to the arrow you see through the glass?

If the arrow does not appear to change then pour off the water and repeat, moving the piece of card closer to the glass.

The science bit

At just the right angle, the arrow on the card should appear to change direction when the glass of water fills up in front of it. When the glass is empty the light travels through glass and air, bounces off the card and back through glass and air before it reaches your eyes.

When water is added the light now travels through glass, water and air. The water bends the light and makes the arrow appear to change direction.

It's the disappearing trick!

3. The disappearing glass experiment

You will need:

  • A glass bowl
  • Glycerine or vegetable oil
  • A Pyrex test-tube

What to do:

  • Pour the glycerine or vegetable oil into the glass bowl until it is three-quarters full.
  • Bend down so you are looking at the glass bowl, from the front, at eye level.
  • Slowly lower the Pyrex test-tube into the bowl, it should be clearly visible.
  • Keep lowering the test-tube into the bowl of oil until the top of the test-tube moves below the level of the oil and starts to fill up with oil.

The science bit

Once the test-tube starts to fill with oil it should appear to disappear. That is because the Pyrex glass and the oil bend the light passing through them in exactly the same way so it appears that the test-tube has disappeared.

*Note: In the studio we used glycerine but you can use vegetable oil instead of you prefer. The vegetable oil should work in place of the glycerine.