بوابة الثانوية العامة المصرية - الوحدة الاولى كاملة Science 5 اتصل على 01144290605

الوحدة الاولى كاملة Science 5 اتصل على 01144290605
الوحدة الاولى كاملة Science 5 اتصل على 01144290605

Lesson “1”Light

- The visible spectrum:
It is the light energy that can be seen.
- The Sun is the main source of light on Earth.

The properties of light

1- Light travels in straight lines.
G.R: The formation of images through narrow holes: Because light travels in straight lines.
- The image is minimized and inverted.
- Formation of shadow.: : Because light travels in straight lines.
- Shadow: It is the darkened area which is formed as a result of falling light opaque object.
2- Transmitting of light through different materials.

A- Transparent materials:

B- Semi-transparent materials:

C- Opaque materials

Allow most light to pass through.

Ex.: Clear glass - Clear water-Air.

Allow some light to pass
Ex.: Tissue paper.

Don’t allow light to pass

- Ex.: Wood - people.

G.R: Our bodies are opaque materials.
Because they don’t allow light to transmit through and objects can’t be seen behind them.
· The clear glass is a transparent material.
Because it allows most light to pass through and objects can be seen clearly through them.
3- The light reflection.
It is the bouncing (returning back) of light rays when light falls on a surface.

Light reflection can be divided into:

Regular reflection:

Irregular reflection:

It is the reflection of light when it falls on a smooth and shiny reflecting surface light rays are reflected in one direction.

Ex.: Mirror surface.

It is the reflection of light when it falls on a rough reflecting surface the light rays are reflected in different directions.

Ex.: White paper.

4- Light refraction:
It is the change in the direction of light rays when light passes through the separating surface between two transparent media due to the change in the light speed.
- The light speed through air is faster than that through water)
- So this change in the speed of light rays causes their refraction (Changing in their direction) and seeing the pencil broken.
G.R.: A spoon appears broken. Due to the refraction of light.
5- Separation (splitting) of light.

White light consists of seven spectrum colors, we can separate it into seven colors by a glass prism.

· Separation of light:
It is the separation of white light into seven colors called spectrum colors.

- White light can be also ****yzed into the seven spectrum by the drops of rain water.

- The seven spectrum colors: Red – Orange – Yellow – Green – Blue – Indigo - Violet