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Just in case you are wondering what MESS is about,
it is a collaborated educational blog.

Find out more at the navigation "MESS"

This blog is officially opened in 21 August 2009




-10 Recent Posts-
P4 Science Chapter 5: Circulatory System
P4 Science: Air & the Respiratory System
P4 Chapter 3: The Water Cycle & Importance of Water
P4 Chapter 2: Water and Changes of States
P4 chapter 1: Matter & its 3 states
P3 Science Chapter 1: Diversity
P3 Science Chapter 7: Life Cycles Of Animals
P3 Science Chapter 8: Life Cycle Of Plants
P3 Science Chapter 9: Heredity
P3 Science Chapter 11: The Human Digestive System


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Tuesday, August 25, 2009
P4 Science Chapter 6: Energy & Light @ 6:32 PM

P4 Science Chapter 6: Energy & Light
Energy is needed to do work. Most of the energy on Earth comes from the Sun.
  • Green plants use light energy to photosynthesize
  • Herbivores eat the green plants
  • Carnivores eat herbivores
  • omnivores eat both plants & meat

Light

Natural Sources of light: Sun, Star

Artificial ":Electrical blulb, Torch

Properties:

  • travels in a straight line
  • can be transmitted
  • can be absorbed
  • can be reflected

Reflection

When light rays travels to a smooth and shiny surface, a regular reflection will occur. When a surface is rough/unpolished, a diffused reflection is formed.

Transparent objects: crystal, glass,clear plastic,water

Translucent: Tracing paper, frosted glass

Opaque: wood, metal, cardboard

Refraction

We know that light travels in straight lines. However, light can also bend when it travels through different substances (eg.water) with different densities. This bending of light is known as refraction.

Try it! Pour a glass of water, and the cup must be transparent. Then put a straw in it. Notice that when you look from the outside, the straw is "bent". This is called refraction.

Absorption

Some objects can take in or absorb light, so they only reflect some or none of the light falling on them. The amount of light absorbed depend on the properties of the materials used to make the object and the colour of light falling on it.

Shadows

When the path of light is blocked by an object, a shadow will be formed.

To form larger and blur-er shadows:
The object must be nearer to the light source.

To form smaller and sharper shadows:

The object must be further from the light source




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