www.childrensdiscovery.org.au www.randwick.nsw.gov.au/library USE THE ITEMS PROVIDED TO LEARN ABOUT LIGHT AND COLOUR. • Please return the box with all equipment packed as you found it. • Report any missing or damaged items to the staff. SPARK DISCOVERY BOXESare to be used with adult supervision AT ALL TIMES. Light and Colour WHAT’S IN THE BOX? Wind-up LED torch Spray bottle (please dry after use) Set of lenses of different types Blank CD Spectroscope 7
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WHAT’S IN THE BOX? - childrensdiscovery.org.au · WHAT’S IN THE BOX? Wind-up LED torch ... • FIND some photos of rainbows. ... Draw the shape of the lens that
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SPARK!� DISCOVERY BOXES � �are to be used with adult supervision AT ALL TIMES.Light and Colour
WHAT’S IN THE BOX?
Wind-up LED torch
Spray bottle (please dry after use)
Set of lenses of different types
Blank cD
Spectroscope
7
2 Light and Colour
What is light?
Light is one type of radiation produced by stars (including our sun), by some creatures and reactions, and by lamps and flames. Similar types of radiation include radio waves, microwaves, infrared, ultraviolet and X-rays.
We can think of radiation as invisible waves travelling through space. We only see things that produce or reflect radiation of certain wavelengths.
From longest to shortest wavelength, most people see red, orange, yellow, green, blue, indigo and violet light. If light of all these colours combines, it appears white.
Can you watch colours mixing?•POURwaterintoatallglassuntilitisabouttwo-thirdsfull.Placeonedropeachofred,blueandyellowfoodcolouringonthesurfaceofthewater,spacedwellapart.Placeasheetofpaperbehindtheglassandwatchthecoloursmix.Doyouseethecoloursyouexpected?
Can you measure light?Scientists often perform simple qualitative experiments when they explore a new field. This is what you did with the CD, exploring and observing light without measuring anything.
To understand more about the world, scientists then devise quantitative experiments, ones that involve measurement. They have invented all sorts of instruments to help in these measurements.
The spectroscope is an instrument for separating the colours in light and measuring their wavelengths. Using spectroscopes, scientists can analyse the chemical composition of distant stars and gain a deep understanding of the substances around us.
In this photo, waves moving from left to right are diffracted by the gap in the barrier, just as light waves are diffracted by a tiny slit.
Grating spectrometer schematic
Light and Colour 7
Why are bubbles colourful?
A bubble is a very thin film of water and detergent. When light hits it, some is reflected by the outside of the film and some is reflected (a short time later) by the inside of the film.
When these two slightly different reflected light waves overlap, some wavelengths (colours) become stronger and others become weaker or disappear.
This effect is called interference. The particular colours you see depend on the time lag and thus on the thickness of the film.