Worksheet 1
Optics and light
Standard No. 10A.29.1
Objects:
1- Know that properties of light.
2- Know the types of light beams.
Key words:
Bundleحزمة / Straight lines خطوط مستقيمة
Beamشعاع ضوئي / Shadow الظل
A parallel beams أشعة متوازية / A divergent beams أشعة متفرقة
A convergent beams أشعة متجمعة / Opaque جسم غير منفذ
Properties of Light summary
1) Light travels in straight lines called rays.
2) A bundle of rays is known as a beam of light (Straight and Narrow).
3) Light travels much faster than sound
4) We see things because they reflect light into our eyes
5) Shadows are formed when light is blocked by an object
Types of light beams
Opaque is an object that light cannot get through.
Shadows are places where light is blocked
Complete the following sentences:
1- Light travels in ………….……………..lines.
2- Light travels ………….…………………….……………..than sound.
3- Shadows are formed when light is ………… by an object.
4- Types of light beams are ……………………., …………………and……………….
Tell me why………………….
1. Thunder and lightning start at the same time, but we will see the lightning first
2. When a starting pistol is fired we see the smoke first and then hear the bang.
3. We see things
Write properties of light.
1- ………………………………………………………………………………
2- ………………………………………………………………………………
3- ………………………………………………………………………………
4- ………………………………………………………………………………
5- ………………………………………………………………………………
ولي الأمر: عزيزي المعلم ......
المعلم:عزيزي ولي الأمر......
Worksheet
Plane mirror
Standard No. 10A.29.1
Objects:
1- light can be reflected by plane surfaces.
2- Explain how images are formed in plane mirrors.
3- Know the properties of image that formed by plane mirror.
key words
Normal عمودي / Incident ray شعاع ساقطThe angle of incidence زاوية السقوط / Law of Reflection قانون الانعكاس
reflected Ray شعاع منعكس / the angle of reflectionزاوية الانعكاس
A real image صورة حقيقية / A virtual image صورة تخيلية
Reversedمعكوسة / Uprightمعتدلة
Summary
A virtual image is formed by a plane mirror. The rays reflecting from the mirror appear to have originated from the location of the virtual image. On a diagram, a virtual image is usually depictedترسم by a broken (dotted) arrow امتداد الأسهم.
A real image (formed by other kinds of optical devices) can be focused on a screenيمكن استقبالها على حائل, whereas a virtual image cannot. On a diagram, a real image is usually depicted ترسمby a solid arrow.
The characteristics of the image
1. The image is located behind the mirror.
2. The image is virtual.( can’t be focused on a screen)
3. The image is the same size as the object.
4. The image is upright (erect).
5. The image is reversed.
6. The image is situated at the same distance from the mirror as the object.
صنف في الجدول التالي الأجسام التالية حسب إنفاذها للضوء:
الخشب / الضباب / الماء / الزجاج / بخار الماء / الحديد / الهواء / الورق
أجسام شفافةتسمح للضوء بالنفاذ / أجسام معتمة
لا تسمح للضوء بالنفاذ / أجسام شبه شفافة
تسمح لجزء فقط من الضوء بالنفاذ
صل بخط بين ما هو متناسب:
الانعكاسReflection / the angle measured from the reflected ray to the surface normal
الزاوية المحصورة بين الشعاع المنعكس والعمود المقام على السطح
زاوية السقوط
angle of incidence / the reversal in direction of a particle stream or wave upon encountering a boundary
ارتداد مسار حركة الجسيمات أو الموجات من على حاجز
زاوية الانعكاس
angle of reflection / angle measured from the ray to the surface normal
الزاوية المحصورة بين الشعاع الساقط والعمود المقام على السطح
قانون الانعكاس
law of reflection / the angle of reflection and angle of incidence are equal
زاوية الانعكاس تساوي زاوية السقوط
اختر من الصفات التالية صفات الأخيلة في المرايا المستوية:
5 / معتدل؛ أي أنه ليس مقلوباً / 5 / بعد الخيال عن المرآة ربع بعد الجسم عنها5 / مقلوب جانبياً؛ أي أن اليمين يبدو أنه اليسار، (معكوسة) / 5 / طول الخيال يساوي طول الجسم
5 / مقلوب؛ أي أنه ليس معتدلاً / 5 / حقيقي؛ أي يمكن جمعه على حاجز
5 / طول الخيال ضعف طول الجسم / 5 / بعد الخيال عن المرآة يساوي بعد الجسم عنها
5 / وهمي؛ أي يتكون خلف المرآة ولا يمكن جمعه على حاجز / 5 / معتدل جانبياً؛ أي غير مقلوب جانبياً
Which of the following are properties of virtual images formed by plane mirrors?
they are inverted
they are upright (erected).
they are left-left and right-right consistent
they are left-right reversed
they are enlarged in size
they are equal in size to the object
they are reduced in size
they are located closerto the back ofthe mirror than the object is in front of the mirror
they are located as far behind the mirror as the object is in front of the mirror
their frequencies (colors) remain the same
their frequencies (colors) are reversed with their complementary colors
they areformed by converging rays
they are formed by diverging rays
they are considered "cool images"
Homework:
What is meant by?
1- angle of incidence:
2- angle of reflection
3- Reflection
4- law of reflection
ولي الأمر: عزيزي المعلم ......
المعلم:عزيزي ولي الأمر......
Uses of curved mirrors
استخدامات المرآيا الكرية
· Car headlamp plus reflector(المرآيا المجودة بكشافات السيارات وتكون مقعرة)
· Car wing mirrorالمرآيا الجانبية في السيارات (مرآيا محدبة)
· shaving/make-up mirror
· satellite TV aerial
· reflecting optical telescope التلسكوب العاكس
· solar furnace الفرن الشمسي
1- What is the type of the following reflections:
…………………………. …………………………..
2- Write missed data of the following shape:
1- ………………………………
2- ………………………………
3- ………………………………
4- ………………………………
5- ………………………………
6- ………………………………
W
3- What is the relation between No. 5 and No. 6
…………………………………………………………………………………………….
4- احسب زاوية السقوط في الحالات التالية
a) اذا كانت زاوية الانعكاس 20 درجة
b) اذا كانت الزاوية بين الشعاع الساقط والمنعكس 60درجة
c) اذا كانت الزاوية المحصورة بين الشعاع الساقط والمرآه 25 درجة
d) إذا كانت الزاوية المحصورة بين الشعاع المنعكس والسطح العاكس 10 درجات
Worksheet
الانكسار Refraction
Standard No. 10A.29.2
11 F.22.5
Objects:
1- Know that light is refracted as it passes from one medium to another.
2- Explain total internal reflection and its application in fiber optics
Key words:
the refractive index معامل الانكسار / Dispersionتشتت
angle of refraction زاوية الانكسار / medium وسط
Angle of incidence زواية السقوط / Bend ينحرف (ينحني)
Snell’s law قانون سنل / Boundary حد (سطح) فاصل
Refraction
It is bending (turning) of light when it passes from one medium into another.
Why does light refract?
Because the speed of light is differs in different materials.
How does the light refract?
1- The ray of light bends TOWARDS the normal (the refracted angle will be smaller).
If the ray of light is moving from
the less dense medium to a more dense
the lower index of refraction to higher index of refraction.
the high speed to low speed
2- The ray of light bends away from the normal (the refracted angle will be smaller).
If the ray of light is moving from
the more dense medium to a less dense
the higher index of refraction to lower index of refraction.
the low speed to high speed
Why do objects at the bottom of an aquarium حوض السمكfilled with water appearيظهر closer أقرب than they actually appear?
What is meant by index of refraction
It is the speed of light in a vacuum (c) divided by the speed of light in “medium” (v)
Problem 1
material / n / material / nVacuum / 1 / Crown Glass / 1.52
Air / 1.0003 / Salt / 1.54
Water / 1.33 / Asphalt / 1.635
Ethyl Alcohol / 1.36 / Heavy Flint Glass / 1.65
Fused Quartz / 1.4585 / Diamond / 2.42
Whale Oil / 1.460 / Lead / 2.6
The speed of light in an unknown medium is measured to be
2.76 x 108 m/s.
(a) What is the index of refraction of the medium where
c = 2.99792458 x 108m/s?
(b) Does it match any of the materials listed in following Table?
Why the spoon ملعقةlooks like it’s broken?
Why does the light refract?
Draw the light ray in the second medium.
The value for the index of refraction, n, of an optically dense medium is allowed to fall anywhere in the range between 0 < n < 1.
The speed of light in a vacuum is 3 x 108 m/sec.
Diagram Questions
According to the diagram shown above, which substance, A or B, is the more optically dense medium?
A / B
According to the diagram shown to the right, which statement is false?
nA = nB
nB > nC
nC < nD
nD > nA
nB > nD
/
Which diagram shown below correctly illustrates the path of a monochromatic ray of light through a triangular piece of glass?
Which diagram shown below correctly shows the path of a light beam passing through a rectangular "air bubble" in a piece of glass?
A / B / C / D
Choose the correct answer:
a) If fused quartz is faster?
The right ray will be A b c d
b) If (angle of refraction > angle of incidence)
The right ray will be
A b c d
c) If fused quartz is slower?
The right ray will be
A b c d
d) If fused quartz same speed as Medium X
The right ray will be
A b c d
e) If there is (No bending)
The right ray will be
A b c d
What's wrong with this picture?
Calculate Speed of light in alcohol if n = 1.36 (Reference Table)
v = c/n
V = (3x 108)/ 1.36
V = 2.21 x 108 m/s
Total internal reflection
The total internal reflection takes place if
i) The angle of incidence is greater than the critical angle C (C=42 for glass , C=49 for water)
The field of fiber optics depends upon the
total internal reflection of light rays traveling
through tiny optical fibers
Dispersion of light
It is the phenomenon of splitting of a beam of white light into its constituent colors on passing through prism.
يحلل المنشور الثلاثي الضوء الأبيض إلى الوان الطيف السبعة كما بالصورة
Formation of a Rainbow
The small droplets of rain water which remain suspended in air just after the rains act like a prism. When sunlight passes through these drops of rainwater, it gets dispersed and we see the seven colors of the rainbow.
The mirage السرابis caused by the total internal reflection of light at layers of air of different densities. In a desert, the sand is very hot during day time and a result the layer of air in contact with it gets heated up and becomes lighter. The lighter air rises up and the denser air from above comes down.
Lenses
A convex lens is a lens which is thicker at the center than at the edges.
A concave lens is thinner at its center.
Fig 3
The curved surface/surfaces of a lens bend the light. Notice the paths of light of the convex and concave lenses shown below.
A convex lens is a converging lens
Convex lens
A concave lens is a diverging lens
Concave lens
The human eye
Our eye is the most important natural optical instrument. The eyes have a convex lens in them. In the eye ,the real ,inverted image is focused by changing the shape of the lens.
Long sight
a person who can see distant objects clearly but cannot focus near object is said to be long sighted .this person should wear a convex spectacles lens
See fig 1
Short sight
a person who can see near objects clearly but cannot focus distant object is said to be short-sighted .this person should wear a concave spectacles lens
See fig below
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