Light & Colour
Water Drop Magnifier
Its so simple to make your own mini magnifying glass. Heres how.Suitable for kids aged 4+You Need:
What to do:
- Small square of fairly-rigid transparent plastic (You can cut-up a clear acetate sheet, or a transparency available from art and craft stores and/or office supply stores. A piece of plastic from a shirt box or the like would also work)
- Half a straw
- Drop of water
- Eye dropper bottle or pipette (optional)
- Staple the straw to the edge of the piece of clear plastic. The straw acts as the magnifiers handle.
- Add a drop of water to the centre of the acetate. It is much easier to apply the drop using an eyedropper or eyedropper bottle, otherwise try the end of a straw or something similar to apply the drop.
- Try not to disturb the drop of water so it stays in a nice rounded shape. The water acts as the magnifiers lens.
- Now try your magnifier out. Hold it close to some small print and watch how the print under the drop of water is magnified. Vary the distance of the drop from the print and see what difference this makes.
Why is it so?The water acts as a lens, just like the lens in a commercial magnifying glass. The convex lens bends light on its return journey from the image underneath the lens to your eye, making the image appear larger or magnified.
Make your own translucent photometer out of paraffin wax that can read light and colour.Suitable for kids aged 6+ with parental supervisionCAUTIONIf you are unable to source your own paraffin wax blocks you will need to make your own. Wax blocks must strictly be prepared by an adult as they involve melting wax and pouring the hot wax into a mould.You Need:
What to do:
- Two small paraffin wax blocks (approx. 8 x 5 x 2cm). If you cant source your own from a supermarket or candle supply centre then you will have to make your own. Instructions in the What to do section.
- Aluminium foil
- Masking tape
- Torch (optional)
- Sheets of coloured paper (optional)
- Prepare two wax blocks of the same size. You might be lucky enough to source boxes of paraffin wax at your local supermarket or hardware store. If so, they often come in slabs that need to be cut in half with a sharp knife to get two blocks of roughly the size required. This must be done by an adult working carefully not to chip or break the slab. If you cant source pre-made blocks, an adult will need to melt down some paraffin wax and pour the hot wax into an appropriate mould from around the house (juice containers, margarine tubs, even a double layer of thick aluminium foil can work). Paraffin wax has a low melting temperature of about 60 degrees celsius and a metal container that fits snugly inside your saucepan is a good option to melt the wax down for moulding.
- With scissors cut a piece of aluminium foil to the same size as your two blocks, and place it in between the two blocks. Just like an aluminium sandwich (with the wax blocks being the slices of bread).
- Wrap masking tape around the two blocks to keep them together and the aluminium foil in place.
- You now have your photometer ready to read light intensity and colour. Hold the block horizontally. Which is brighter, the top or bottom block? If it is the top block, your photometer is telling you that the top half of the room is brighter than the bottom. Hold it vertically. Which half of the room is brightest? Spread out some different coloured paper on the floor or a table and run your block over the top. Dont touch the paper with your block. You should see the bottom block turn a pale version of the colour of the paper underneath it.
- As a further experiment, shine a torch light into one side of the block. In that way you can compare the intensity of the torch light to the light source on the other side of the photometer.
Why is it so?The wax is a translucent material, the light can enter and is reflected back through the block by the aluminium foil. Thus you can measure light intensity by the brightness of the block. You can compare the light intensity of two different light sources by placing each light source on opposite sides of the block, which ever block shines the brightest is indicative of the more intense light source. You can also read colour because the coloured light is also reflected back through the block by the aluminium foil.
Split light without a prism
Want to make a rainbow but dont have a prism? Heres a simple way to make one anytime the sun is shining. Youll be beaming from ear-to-ear.Suitable for kids aged 5 +You Need:
What to do:
- Shallow dish
- White wall (or large piece of white paper/card)
- Small mirror
- Sunlight (the stronger the better)
- Pour some water into the shallow dish.
- Place the small mirror in the water and prop it at an angle against the side of the dish.
- Put the dish near a sunny window and position the mirror so that sunlight bounces off it onto a white wall.
- If you dont have a white wall you can use a large piece of white card or paper attached to the wall.
- You should see a faint rainbow appear on the white wall or paper. If not, adjust the mirror until you see it.
Why is it so?The water in the shallow dish acts like a prism. When the sunlight travels from air into water it slows down and bends. The seven different colours that make up white light travel at different speeds and therefore bend at slightly different angles. The mirror reflects the different colours so the rainbow spectrum appears on the wall.
Turns out theres a lot more to white light than meets the eye. Here's a simple spectrometer you can build yourself, using just a spare CD, an empty cereal box and a pair of scissors.Suitable for kids aged 11 +You Need:
What to do:
- Cereal box
- Compact Disk
- Utility knife/Scissor
- Cut a 1" slit on the side of the cereal box just below the nutrition information.
- Cut a slit across the opposite side of the box and extend it 1" on either side at an angle 45 degrees above the horizontal. Use a protractor to measure the exact angle.
- Slide a CD into this slit.
- Make an eye hole on the bottom of the box below the CD.
- Point your spectrometer at a bright light source and look through the eye hole!
Why is it so?Light can be split into its spectrum of colours using a spectrometer. Different light sources will give different spectra through the spectrometer. Different spectra or "rainbows" are displayed from different light sources because they are made up of different elements.
For example a street light will have a different spectra to a laptop screen, as old street lamps are primarily made up of the element sodium, which gives off a strong yellow colour, as can be seen when burning Sodium Chloride! How do scientists know which elements make up far away stars? They point their spectrometers at them and analyse their spectra, from the spectra and black lines that are observed, scientists are able to deduce what gases stars are composed of. The spectra of our sun shows that it is made of mainly hydrogen! WOW!