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How much do you know about light?
How much do you know about light?
Well, for starters, it’s the fastest thing in the Universe and can travel around the Earth 7.5 times in one second! Let’s fi nd out more…
Light is how we see the world around us and why diff erent things are diff erent colours. When we see the things around us in the daytime, we are seeing the light that comes from the Sun bouncing off whatever we are looking at!
So how come there are so many different colours around us when the light from the Sun appears to be just one colour? Even though light from the Sun is white, it actually contains all the colours of the rainbow.
IN RAINBOWS
IN RAINBOWS
Rainbows appear because of refraction – but it’s a raindrop that splits white light into its different colours. The light then refl ects, bouncing off the back of the raindrop and spreading out as it comes out of the raindrop. When we see the light coming from all of the raindrops at once, we see a rainbow! The best way to see a rainbow is if the Sun is behind you and the rain is in front of you. The light fl ies over your head, bounces off the rain and comes back into your eyes.
video
video
SHADY SHADOWS
SHADY SHADOWS
We cast a shadow because light shines in straight lines and cannot bend around objects unless they are transparent, like a window, or are reflective, like a mirror.
REMEMBER!
REMEMBER!
Never look directly at the Sun because it’s so bright it can damage your eyes. On a sunny day it’s a good idea to wear sunglasses to protect your eyes – but even then you still shouldn’t look directly at the Sun.
how do we see?
how do we see?
When light hits the retina (a light-sensitive layer of tissue at the back of the eye), special cells called photoreceptors turn the light into electrical signals. These electrical signals travel from the retina through the optic nerve to the brain. Then the brain turns the signals into the images you see.
BENDING THE LIGHT FANTASTIC
BENDING THE LIGHT FANTASTIC
You can split white light into all the different colours by shining it through a triangular piece of glass called a prism. Each colour bends a different amount – at one end is red, which gets bent the least, and at the other end is purple, which bends the most. Bending light is called refraction
videos
videos
WHAT MAKES SOMETHING ONE COLOUR RATHER THAN ANOTHER?
WHAT MAKES SOMETHING ONE COLOUR RATHER THAN ANOTHER?
This is all to do with how the light bounces off an object. Some colours are absorbed in the surface of the object, while other colours are refl ected back out. A green leaf looks green because it refl ects the green part of the white light back to you, while it absorbs all the other colours.
THE ELECTROMAGNETIC SPECTRUM
THE ELECTROMAGNETIC SPECTRUM
Light is an electromagnetic wave. It’s just one of a whole range of different electromagnetic waves, all of which have different wavelengths – some waves are bigger than others (see above). Scientists organise the biggest to the smallest wavelengths on a scale called the electromagnetic spectrum. Here are some of the waves that the electromagnetic spectrum contains…
Radio waves are used for radio and TV signals. They have the biggest wavelengths.
Microwaves are used to heat up food or to transmit our mobile phone signal.
Visible light lets us see the world around us.
Ultraviolet comes from the Sun and can hurt our skin – it’s why we wear suncream!
X-rays go right through you and bounce off your bones, so they’re useful for scanning inside your body in a hospital.
Gamma rays have the highest energy and the smallest wavelengths. They’re used in hospitals to help kill cancers, but they can also be harmful. We use a radiation symbol to warn others if something is radioactive and dangerous.
videos
videos
LIGHT AND COLORS
LIGHT AND COLORS
worksheets
worksheets
LightandColorBillNyetheScienceGuy-1.pdf
color with m&M's
color with m&M's
LightandColorwithMMs-1.pdf
grade 1 worksheets
grade 1 worksheets
light1.pdf
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