LIGHT AND HEAT

LIGHT

Light is a form of energy. Light can come from a natural source such as the Sun or lightning or from an artificial source such as a torch or a candle. It travels at 300 000 kilometres per second. It is made up of seven colours. It travels in a straight line.  

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PROPERTIES OF LIGHT

Objects can be transparent if they allow light to pass through them. Objects can be translucent if they allow  some light to pass through them. Objects are opaqueif they don´t allow any light to pass through them. Sunlight is an example of white light. It is made of seven colours. You can see these colours in a rainbow. When Light hits an opaque object some colours are absorbed and others are reflected.

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REFLECTION OF LIGHT

Reflection happens when light hits an object and bounces back. It could be a smooth surface such as a mirror or a rouge surface such as the water in a lake when you throw a stone 

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REFRACTION

Refraction occurs when light changes direction as it passes from one substance to another.  Lenses are a good example of refraction. 

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HEAT

Heat is the flow of thermal energy from a warm substance to a cooler substance. Some materials are thermal insulators because they don´t transfer heat sucha as wood, wool and plastic. Some materials are thermal conductors because they transfer heat such as iron, copper and aluminium.

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EFFECTS OF THERMAL ENERGY

MELTING:: When we add thermal energy to a solid it becomes liquid. EVAPORATION: When we add thermal energy to a liquid, it becomes a gas. EXPANSION: The volume of a substance increases when we add thermal energy.

Unit 12: Heat, Light & Sound | KLU Science (Embed)