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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
