Lesson 1 Reflection. الانعكاس Optics الفهرس 1.الانعكاس 2.الصور في...

Lesson 1

Reflection

Opticsاالنعكاس

الفهرساالنعكاس1.الكروية 2. المرايا في الصوراالنكسار3.العدسات 4. في الصوراالنكسار 5. تطبيقات

Goalsاألهداف

لالنعكاس 1. األول القانون

لالنعكاس 2. الثاني القانون

االنعكاس 3. نوعا

المستوية 4. المرآة

key wordsالمصطلحات

عاكس • reflecting surfaceسطحالساقط • الشعاعاالنعكاس • عمودالمنعكس • الشعاع

السقوط • زاويةاالنعكاس • زاوية

لالنعكاس • األول القانونلالنعكاس • الثاني القانون

منتظم • انعكاسمنتظم • غير انعكاس

Activity-1نشاط -

Activity-2نشاط-

؟ العلمي المصطلح ماارتداد األشعة الضوئية عن السطح العاكس …………………………………………1.

شعاع ضوئي يسقط من المصباح على السطح العاكس …………………………………………2.

شعاع ضوئي يرتد عن السطح العاكس …………………………………………3.

الخط المعامد للسطح العاكس عند نقطة سقوط األشعة على …………………………………………4.السطح العاكس

θi الزاوية المحصورة بين الشعاع الساقط و عمود االنعكاس …………………………………………: 5.θrالزاوية المحصورة بين الشعاع المنعكس و عمود االنعكاس ………………………………………… : 6.

” زاوية السقوط = زاوية االنعكاس“……………………………………………………………………………7.

عمود و الشعاع المنعكس و الشعاع الساقط……………………………………………………..………………………8. االنعكاس

W في مستوى واحدتقـــع السطح العاكس عمودي على جميعا

Law of reflectionLaw of reflection

R

Planar reflecting surface (mirror)

= angle of incidence

R = angle of reflection

1st Law of reflection

Ri

Activity-3نشاط-

جد • ثم االنعكاس و السقوط زاوية من W كال الرسم على عين-: منهما كٍل] مقدار

40O

مـــرآة

θi=

θR=

نوعا االنعكاس•.................... انعكاس................ انعكاس

•.................... السطح................ السطح

الحالتين؟ ..........• كلتا في االنعكاس قانونا يتحقق هٍل

صفات الصورة في المرآة المستوية

Objects and imagesObjects and images

Object Image

Rays from point on object reflect

from mirror

Reflected rays appear to come

from a point

17.1 Reflection

• Images appear in mirrors because of how light is reflected by mirrors.

• The incident ray follows the light falling onto the mirror.

• The reflected ray follows the light bouncing off the mirror.

Objects and imagesObjects and images

Object Image

Rays from point on object reflect

from mirror

Reflected rays appear to come

from a point

صفات الصورة في المرآة المستوية

خلف )حقيقية / وهمية (الصورة:- 1.المرآة

gعد الصورة2. gعد ب )أكبر / يساوي / أصغر ( بالجسم

حجم الصورة )أكبر/يساوي / أصغر ( حجم 3.الجسم

الصورة ) مقلوبة / معتدلة (4.

.5W الصورة مقلوبة جانبيا

حجم الصورة يساوي حجم الجسم

W الصورة مقلوبة جانبيا

التقويم

بعـد • على سعيد .2mيقف مرآة منسعيدعن 1. صورة بعد المرآة؟ ما

…………

؟ 2. عنه صورته بعد ………… ما

بسرعة • المرآة من طفٍل .0.4m/sيقتربالمرآة؟ – من الطفٍل صورة اقتراب سرعة ما

……………صورته؟ – من الطفٍل اقتراب سرعة ما

……………

Hall MirrorHall Mirror

•Useful to think in terms of Useful to think in terms of imagesimages

“image” you

“real” you

mirror onlyneeds to be half as

high as you are tall. Yourimage will be twice as far from you

as the mirror.

Activity-4نشاط -

كاملةW؟ صورتك لكي الالزم المستوية للمرآة المطلوب الطول ما

Example 1A device consists of 2 mirrors at right angles to each other.Complete the path of the ray.

M1

45

M2

4545

The ray is turned back .

parallel but

opposite in direction

parallel but

opposite in direction

virtual1 behind the mirror;

2 of same size as the object

3 laterally inverted

How a plane mirror forms an image

Properties of the image formed by a plane mirror

mirror

object

Fimage

4 Image and object are

equally distant

• by geometric construction

O I

virtual rays shown by dotted lines

Locating the position of the imageLocating the position of the image

3 How a plane mirror forms an image

• I is a virtual image.– cannot be picked up on a screen

Reflected rays appear to come from I behind the mirror.

mirror

O

3How a plane mirror forms an image

I

Q3True or false: Reflection of…

True of false: Reflection of light by a rough surface does not obey the laws of reflection.

)T/F(

Q2The angle between an…

The angle between an incident ray and the mirror is 20.The angles of incidence and reflection are ____ and ____.

The mirror turns the ray by ____ .

70 70

140

2070 70

Q1The angle between the…

The angle between the incident ray and the _______ is called the angle of incidence.normal

The laws of reflection state that it is equal to the angle of ___________.reflection

Diffuse reflection

• on a rough, not perfectly smooth surface

• e.g. cover of a book

parallel incident rays

reflected rays in different directions

2Regular and diffuse reflection

Regular reflection

parallel incident rays

parallel reflected rays

• on a flat, smooth surface• e.g. mirror

2Regular and diffuse reflection

• The incident ray,the reflected ray and the normal all lie in the same plane.

normal

incident ray reflected ray

mirror

normal

incident ray reflected ray

mirror

1st Law of reflection

reflected rayincident ray

normal

mirror

angle of incidence

angle of reflection

2nd Law of reflectionAngle of incidence = Angle of Angle of incidence = Angle of

reflectionreflection

•The Law of ReflectionThe Law of Reflection

Angle of incidence = Angle of Angle of incidence = Angle of reflectionreflection

In other words, light gets reflected from a surface at ____ _____ angle it hits it.

The same !

!!

Using filters•Filters can be used to “block” out different colours of

light:Red Filte

r

Magenta

Filter

Clear vs. Diffuse Reflection

•Smooth, shiny surfaces have a clear

reflection:

Rough, dull surfaces have a diffuse reflection.

Diffuse reflection is when light is scattered in different directions

•The Law of ReflectionThe Law of Reflection

Angle of incidence = Angle of Angle of incidence = Angle of reflectionreflection

In other words, light gets reflected from a surface at ____ _____ angle it hits it.

The same !

!!

Part 2 - Reflection•Reflection from a mirror:

Incident ray

Normal

Reflected ray

Angle of incidence

Angle of reflection

Mirror

ReflectionReflection•We describe the path of light as straight-line raysWe describe the path of light as straight-line rays•Reflection off a flat surface follows a simple ruleReflection off a flat surface follows a simple rule::

–angle in (incidence) equals angle out (reflection)–angles measured from surface “normal” (perpendicular)

surface normal

sameangleincident ray exit ray

reflected ray