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Explanation of a Scientific Idea

Light derive from electromagnetic radiation and our eyes are able to see only visible

light (Light and Colour, 2001). For example, the sources of lights are sun, candlelight, and

others. The sun is one of the sources which produce full spectrum of visible light. This light

is known as white light and it can be divided into seven colours or known as rainbow colours

(National Aeronautics and Space Administration, Science Mission Directorate, 2010). By

using spectrum, we can see how white light split into seven colours (refer diagram 1). The

colours are red, orange, yellow, green, blue, indigo and violet.

Diagram 1

Adapted from Educational resource pages for parents and their students.

http://www.valdosta.edu/~mgvaldez/resource.html

Light travel in a straight line. The speed of light is 300,000 kilometres per second.

Light do not need any medium to travel which means it is able to travel in a vacuum (Light

and Colour, 2001). By using lens, light can be refracts. Diagram 2 shows how light are

refracted by converging lens and diverging lens.

Diagram 2

Adapted from Lenses

http://www.math.ubc.ca/~cass/courses/m309-01a/chu/MirrorsLenses/lenses.htm

http://www.math.ubc.ca/~cass/courses/m309-01a/chu/MirrorsLenses/lenses.htmhttp://www.math.ubc.ca/~cass/courses/m309-01a/chu/MirrorsLenses/lenses.htm

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In order to see something, we need four main aspects which are source of light, eye

and retina, a connection from the eye and retina to brain and brain to process the information.

Light help us to see by providing a reflection from a source or object into our eyes (Light,

2009). In diagram 3, it shows how light move and reflect on a surface to be seen through our

eye.

Diagram 3

Adapted from Integrated publishing

http://www.tpub.com/content/neets/14182/css/14182_25.htm

Shadow will be form on an area which the light is not able to pass through an opaque

object (Shadows, 2001). The size of shadow will be differing based on the length between the

light source, opaque object and the surface. Diagram 4 shows how the shadow is formed.

Besides opaque object, there are also transparent object and translucent object. The opaque

object will create shadow when the light is not able to pass it. Meanwhile, transparent object

let the light to pass through it such as water. The translucent object let less light to pass

through it and create a fuzzy shadow which means the shadow cannot be seen clearly. The

examples of translucent object are plastic bags and waxes.

Diagram 4

Adapted from Earth, sun and moon.

http://www.mundesleyjuniorschool.com/InternetResources/Science/Y5/earthsunmoon/shado

ws.shtml

http://www.mundesleyjuniorschool.com/InternetResources/Science/Y5/earthsunmoon/shadows.shtmlhttp://www.mundesleyjuniorschool.com/InternetResources/Science/Y5/earthsunmoon/shadows.shtmlhttp://www.mundesleyjuniorschool.com/InternetResources/Science/Y5/earthsunmoon/shadows.shtmlhttp://www.mundesleyjuniorschool.com/InternetResources/Science/Y5/earthsunmoon/shadows.shtml

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The accuracy or the appearance of shadow varies based on type of light source, and

type of object. Besides that, the surface where the shadow appears also influences the

accuracy of the shadow. The medium where the light travel also might affects the shadows.

For example, if the light source travels through smoke or cloud before it reaches the opaque

object, it will affect the shadow appearances compared to travel in clear air. Diagram 5 shows

how shadows are form on a translucent surface which make it become quite fuzzy.

Diagram 5

Adapted from BBC sport

http://news.bbc.co.uk/sport2/hi/other_sports/swimming/6478919.stm

The shadow form on a solid or opaque surface will be more accurate compared to

translucent surface. However, the light source also will affect the shadow whether it will

become darker or lighter. For example, a small and accurate light source will create a dark

shadow with sharply define edges (Shadows, 2001). The large source of light will create a

dark shadow on the centre and fuzzy images on the outside of the shadow. Besides that, the

angle which the light source attach the object also will affect the size and shape of the

shadow. For example, if a boy stands under the sun in the morning, his shadow will be longer

than his actual height. In contrast, if the boy stands under the sun in the afternoon, the shadow

will be shorter than his actual height. Diagram 6 shows the relationship between the angle of

light source and shadows.

shadow

Morning Afternoon

Diagram 6

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References

BBC sport. (n.d.). Retrieved from

http://news.bbc.co.uk/sport2/hi/other_sports/swimming/6478919.stm

Educational resource pages for parents and their students. (n.d.). Retrieved from

http://www.valdosta.edu/~mgvaldez/resource.html

Integrated publishing (n.d.). Retrieved from

http://www.tpub.com/content/neets/14182/css/14182_25.htm

Lenses. (n.d.). Retrieved from http://www.math.ubc.ca/~cass/courses/m309-

01a/chu/MirrorsLenses/lenses.htm

Light. (2009). Retrieved fromhttp://www.explainthatstuff.com/light.html

Light and Colour. (2001). Wellington, New Zealand: Learning Media Limited.

National Aeronautics and Space Administration, Science Mission Directorate. (2010). Visible

Light. Retrieved fromhttp://missionscience.nasa.gov/ems/09_visiblelight.html

Shadows. (2001). Wellington, New Zealand: Learning Media Limited.

http://www.valdosta.edu/~mgvaldez/resource.htmlhttp://www.explainthatstuff.com/light.htmlhttp://missionscience.nasa.gov/ems/09_visiblelight.htmlhttp://missionscience.nasa.gov/ems/09_visiblelight.htmlhttp://www.explainthatstuff.com/light.htmlhttp://www.valdosta.edu/~mgvaldez/resource.html