Science : Light

Done by: Syazana , Aqirah, Crystal , Azaad, Riqa.

Defination of light.

Light is an important soutrce of energy.it enables us to see.The sun is the most important source of light.infact,without sunlight,it would be impossible for living things to surviveon earth.

Rays and Beams

We know that light travels in a straight lines. We can trace the path of light from a source by drawing straight lines to join one point to another.Such lines are called light rays.A bundle of light rays is known as a beam of light.Beams of light can be parallel,divergent,convergent.

Reflection.

When light rays hit the surface of another medium, it can be reflected. If the surface is smooth, for excample the surface of a mirror, regular reflection takes place. A clear and indistorted image can be seen in the surface. When yo stand in front of a mirror, you can see your reflection on the mirror's surface.

Reflection.

If the surface is rough, for excample the surface of this page, irregular reflection takes place. The surface can be seen, but no reflected images are seen it. For excample, when light shines on a sheet of paper , no reflected image is formed although light is reflected..

Characteristics of plane mirror images.- the distance of the image from the mirror is equal to the distance of the object from the mirror.- the image and the object are the same size-the image is upright.-the image is laterally inverted. This means the left and right side of the image are reversed.-the image is virtual. This means that the image cannot be projected onto a screen behind the mirror.

Types of mirrors

– Plane mirrors– Concave mirrors– Convex mirrors

Plane mirrorsPlane mirrors are most commonly used to check one's appearance. They are also use as a form of decoration to make a room appear spacious. Plane mirrors are used in cars as rear-view of side-view mirrors.

Concave mirrorsNot all reflecting surface are flat like the plane mirrors. Concave mirrors are mirrors with curved surface that bends inwards. When the object is near the concave surfac, images formed are vitual and magnified. Try looking at the front of the shiny metal spoon. Does your reflection appear bigger?

Convex mirrors.Mirrors that bend outwwards are called convex mirrors. The back of the spoon is an excample. Side-view mirrors of cars are sometimes convex mirrors. Convex mirrors cover a wider field of vision , and the images formed are distorted and smaller.

Refraction.

We know that light travels in a sraight lines. But there are times when light bends.

When light rays travels from one medium to another medium of a different density ( for excample from air to water. ), the light ray changes its direction and bends. This bending of light is known as refraction.

End of our presentation :]]]