Food

All animals - including humans - need to eat food. Some eat plants, some eat animals and some eat both. Cows eat grass so they are Herbivores. Snakes eat animal, so they are Carnivores. Humans eat plants and animals so we are Omnivores.

Images created by a plane mirror

The image we see ourselves is:

• The same size as we are. If you are 2m tall, your image in the plane mirror will also be 2m tall. The same distance behind the mirror as we are in front of it. If you stand 1m in front of a plane mirror, your image will be 1m behind it. But... the image we see back to front. Our right hand side appears on the left hand side of the image. We say that the image is laterally inverted.

Images Created By a Plane Mirror

If we stand in front of a plane mirror we see images of ourselves behind the mirror. But if wee lock behind the mirror there are no images there. We are tricked into seeing something that is not really there. Images like these are called virtual images.Rays of light from an object in front of a mirror are reflected into our eyes.

 

Reflection

When a ray of light strikes the surface of a smooth object such as a plane, mirror, it is reflected in a particular way.A ray of light is reflected from a plane surface at the same angel as it hits it. 


The periscope is an optical instrument used to see over high objects or around corners. A periscope is able to do this because it contains two plane mirrors that change the directions of the rays of light.

Shadows

If an opaque object is placed between a light source and a screen, a shadow of the object is created. The shadow has the same shape as the object. This again suggests that rays of light travel in straight lines. The ray diagram below shows how a shadow is created.

Light (Transparent, opaque and translucent)

We are able to see objects on the other side of a pane of glass because the glass because the glass is transparent. 

We are unable to see what is happening on the other side of a wall because the bricks will not allow light to travel through them. The bricks are opaque. 

Some objects allow light to pass through them but scatter the rays of light as they do so. As a result we are unable to see clearly through them. Materials such as these are translucent. Frosted glass is an example of a translucent material.

  

Ray diagrams

Because light travels in straight lines we can use line diagrams, more usually known as ray diagrams, to describe a ray of light as it travels.

We see luminous objects because some of light they emit enter our eyes.

We see non-luminous objects because some of the rays of light they reflect enter our eyes.

RAY DIAGRAM

NON LUMINOUS OBJECT
LIKE EARTH AND STARS  

(doesn't makes its own light) .

 LUMINOUS OBJECT WHICH MAKES

 ITS OWN LIGHT.

Light travels in straight lines. 

>Light is able to pass through

   a straight tube. 

     

>But not through a curved tube.

                                                            

Light

Light travels so Fast that:

>it takes light from the Sun just 8 minutes             

  30 seconds to reach the Earth.

>Light reflected from the Moon takes just 1.3

  seconds to reach the Earth.

>A ship 10 km from a lighthouse would receive

  its light just 0.000 03 seconds (or 300 000 of

  a second ) after it was emitted.

  

       

Light

Many films and television programs set in the future show spaceships travelling between planets and galaxies in extremely short periods of time. You will often hear characters in these productions saying that they are travelling faster than the speed of light. But what do they actually mean?

When light is emitted from a lamp, a torch or the sun, it travels very quickly. In fact, light travels at the amazing speed of 300,000 km per second!!!

                                                      8 minute

                                                      30 seconds

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light reaching to Earth