Rainbows
are beautiful arcs of colour in the sky.
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They occur when it
is raining and sunny at the same time.
To see one you have to stand with
your back to the sun. |
The sun gives off light. The light we
can see is called 'white light'. But this white light isn't
actually white at all, it is made up many different colour
wavelengths.
The main colours are red, orange, yellow,
green, blue, indigo and violet. These seven colours are
called the colours of the spectrum. The longest wavelength
is red and the shortest is violet.
Many people use
the phrase 'Richard Of York Gave Battle In Vain'
to help them remember the colours of the rainbow.
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Separating
the colours
To separate these seven different colours
from the white light, you can use a prism (a triangular-shaped
piece of glass).
The prism separates the white light into
the different colour wavelengths by bending each light
ray at a different angle and so separating the colours.
The separation of white light into different colours is
called 'dispersion'. When the prism bends each light ray,
this is called 'refraction'.
So the reason we get rainbows in the sky
is because the raindrops act like lots of tiny little prisms.
As the sun shines white light through the sky, the raindrops
separate it into the seven main colours, forming a rainbow.
Activities
Why not try creating your own phrase to
remember the colours of the rainbow?
Why not draw your own rainbow and
then colour it in? Try to use the right colours in the
right order.
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