Luminous, non-luminuos, how do we see things

Ray model of Light Teacher: Đặng Thái Nhật Luminous and non-luminous, How do we see t hings... Natural light: Ánh sáng tự nhiên Artificia l light: Ánh sá ng nhâ n tạo... Nat ur al Ar t

Ray model of Light

Teacher: Đặng Thái Nhật

Luminous and non-luminous,

How do we see t hings

Sour ces of Light ?

Are the following pictures all sources of light?

I f not, why and where does the light come from?

Natural light: Ánh sáng tự nhiên

Artificia l light: Ánh sá ng nhâ n tạo

Tor ch

Can you t hink of any

ot her s?

Nat ur al Ar t ificial

Light that nature makes

Light we cannot turn on and off

Light that people make

We can turn these lights on and off

What is Light sour ce?

A light source (or Luminous object)

is anything that makes light, whether

natural and artificial

Natural light: Ánh sáng tự nhiên

Artificial light: Ánh sáng nhân tạo

Object: vật thể

Non Luminous object s:

- Do not emit their own light

- Examples: Moon, Mirror, Pencils, a dog, …

Luminous object s:

- Emit their own light

- Examples: Sun, Fire, Firefly, torch, candle, lightning, …

Object: vật thể

Firefly: con đom đóm

Torch: đèn

Lightning: tia chớp

How do we see object s?

Because of Light

How Does Light Help Us See?

Rays of light travel from a light source and hit objects around us

The rays of light reflect , off an object, and then travel into our eyes

This reflection of light allows us to see the object

1 Light from the light bulb travels in a straight line and hits the chair

2 The ray of light is

reflected off the chair

and travels in a

straight line to the

girl’s eyes, enabling

her to see the chair

Can you describe how you can see some objects right now?

Reflect: dội lại, phản xạ lại

Summar y:

1 Light source (or Luminous objects): are anything that can emit

their own light

2 Non – luminous objects: are anything that cannot emit their own light

3 Light travels in straight line

4 We see things because Light hits to the objects then reflected to our eyes