light

LIGHTBy : Firman

Luminous Object

Luminous object is a object that can shining by itself or emit light by itself.

Example : Fire , sun , lamp.

Non luminous object

Non luminous object is a object that cannot emit light itself they can only reflecting light.

Example : Moon, Table , Chair ,etc.

Light Rays

Light rays is a line of light. Light travel in all direction. Line of light can be seen clearly if they

travel in one direction.

Classifying non luminous object

Transparent let light to pass on. Ex: Glass , windows.

Translucent not let pass some light but pass some light through them. Ex : Tracing Paper

Opaque not let all light to pass through them. Ex: wood, metal.

Shadows

As light cannot pass through opaque object it will make a dark area usually behind the object it was called shadows.

Te size of the shadows depends on the light source and the distance of the light source and the object.

Comparison of the light source

The greater the light source there will be a shadow that have dark in the middle and grey surround it.

The less the light source the darker the shadow in the middle part.

The Distance Between The Object and Light Source

The further the distance between the object and the light source will make small shadow.

The shorter the distance between object and light source it will make a big shadow.

Reflecting light

You can see object because the object is reflecting the light and the reflected light will be caught by our eye.

The study of reflection

Incident ray is a light that strike the surface of something.

Reflected ray is a light ray that is reflected from a surface

Normal is a line that is perpendicular at 90 degree to the surface where a ray strike.

Angle of incidence is the angle between incident ray and normal.

The study of reflection

Angle of reflection is the angle between reflection ray and the normal line.

Plane mirror is a mirror with flat surface. Image is appearance of an object in

smooth shiny surface.

Object with smooth surface

When light ray strike a smooth surface the angle of reflection is equal to the angle of incidence.

When reflected light reach your eyes you will be able to see the image.

Two kind of images

Real image Virtual image

Explanation of images

Real image is a image that can be projected into flat surface.

Virtual image is a image you see in a mirror that are in the same size but only in opposite directions.

Object of rough surface

Light rays that strike the rough surface will not have same angle of incidence and angle of reflection.

Because of this effect you will not able to see your image in the rough surface thing.

Refraction

Refraction is light that is bend because of different position of object and different medium.

The angle which the ray makes with normal is called angle of refraction.

Refraction

Light travel in different speeds in different media.

If the light slows down it bends toward the normal.

A light ray can appear different direction than the actual place example stone in water.

The Periscope

Periscope is an equipment made by two plane mirror

The prism

If the sun light strikes the prism in certain angle and stop by a white screen it will make a range of color is spread out and called as spectrum.

The sun light contains different color because have different wave length and travel in different speed.

Rainbow

Rainbow are appear because of the refraction and reflection of the sun light by the water droplets.

There can be two rainbow if there is 2 reflection occur.

Colour

Absorbing color Reflecting color

Absorb and reflecting color

If all the colors are reflected the color will seem to have white color

If all colors are absorb the color of the object will seem black.

Usually object absorb some color and reflected other colors.

Filtering color

Because some object reflecting and absorb some color so if you put blue glass the only color that can be pass through is blue and the other reflected.

Combining color

When different type of light color is mix up it can make new color. Ex blue and red become magenta.

When three beams of light is shining into white screen it will produce 3 secondary color and white color.

Thank you