Speed of Light

• Electromagnetic waves move through space at the speed of light, about 300 million meters per second (3.0x10⁸m/s).

• They slow down very slightly as they pass through matter.

• The speed of light is believed to be the maximum speed at which anything in the universe can travel.

Light cannot bend over the wall to enable us to see the objects behind the wall

Based on this experiment we know that we can see object in straight line

Opaque Object

is the object are not allow light to pass through them at all

For examples: wood, metal, some plastics, cardboard, and clay

Transparent Object

is the object that allow light to pass through them, so we can see it clearly

For examples: glass, some plastics appear clear

Translucent Object

is the object that allow only some light to pass through them

For examples: some paper, plastic cloth , frosted glass

Shadows

is formed because light travels in a straight line, it cannot bend to move around objects.

Shadows and sizes of shadows

• 1. Shadows formed when tin is placed upright

• 2. Shadows formed when tin is placed lying down

• 3. Shadows formed when light source is close to object

• 4. Shadows formed when light source is far from object

Light can be reflected from surfaces

Many objects around us are not sources of light ,however we are able to see them because they reflect light into our eyes

Light reflected from different surfaces

• 1. A smooth surface reflects light in the same direction

• 2. A rough surface reflects light in different directions

Reflected of light from a mirror

Based on this picture we know the process:

Object reflects light from the lamp onto the mirror then the mirror reflect the light into our eyes

Objects that reflect light are:

• Mirrors

• Tin

• Metals

• Foil

• White/light colour objects