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“TRICKS TO REMEMBER THE SPHERICAL MIRROR AND THE

RAY DIAGRAM OF LENSES”

ACTION RESEARCH REPORT

Guide: Ms. Archana Tomar Investigator: Sugandha Singh

School Of science and education

Navrachana university

Vadodara

2014-2015

B.Ed

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CERTIFICATE

This is to certify that Miss Sugandha Singh has completed action research as a

part of B.Ed program entitled “Tricks To Remember the Spherical Mirror and

Ray Diagram of Lenses”. She has completed it to the best of her capacities and to

the best of my Knowledge, this is her original work.

Guide: Ms. Archana Tomar

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Acknowledgement

When I was in Tejas Vidyalaya for my practice teaching phase I came across the knowledge of problematic

area of students regarding to remember the “Spherical Mirror and Ray Diagrams of lenses”, so I decided to

give them source of important tricks to solve these problems in my action research because they always told

me during my period with them that “is there any way to remember the Ray Diagrams of lenses and Types

of Spherical mirrors and How these mirrors are different from Plane Mirrors ”.So, first of all I want to

thanks the students of class 7th for giving me the opportunity for finding some way for easily remembrance

of the Ray Diagrams of Lenses.

My sincere thanks go to Mr. P.V. Xavier, principal of Navrachana University who gave me the opportunity

to do such a wonderful research with students and also Ms. Archana Tomar for her ideas and help during

action research teaching phase.

I would like to express a deep sense of gratitude to Ms. Sumita Mam , Science Teacher of Tejas vidyalaya

who guided me throughout the teaching phase to meet the desired problem goal for solving the problems by

identifying most suitable way to teach the tricks.

I am thankful to my co- teacher pupils who motivate me, inspired and helped me while doing my practice

teaching and Action Research.

Sugandha Singh

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Sr. No. Content Page No.

1

Abstract

2 Intoduction

3 Specific Question

4 Research Setting

5 Review

6 Research Method

7 Objective of the study

8 Participants

9 Data Collection Tool

10 Process of Data Collection

11 Analysis of Data

12 Research Finding

13 Conclusion

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ABSTRACT

Mirrors are the basic means of viewing our own beauty. Generally a mirror refers to plane mirrors. But if

the surface of a mirror is a part of a sphere we call it as a spherical mirror. There are two types of mirrors:

Plane mirror and curved mirrors. If the curved mirror is a part of a huge sphere, then the mirror is a spherical

mirror.

Spherical mirrors can be further classified into two types- Concave mirrors and convex mirrors. If a part of a

hollow glass sphere is cut, its outer surface is convex and its inner surface is concave. If cut part of the

sphere is coated outside with silver or similar material, then its inner surface reflects the entire light incident

on it, and thus, forms a mirror. Since the inner surface is a concave surface, the mirror so formed is called a

concave mirror.

Newton’s fundamental contribution to mathematics, mechanics, and gravitation often blind us to his

experimental and theoretical study of light. He made pioneering contributions in the field of optics. He

further developed the crepuscular model of light proposed by Descartes. It presumes that light energy is

concentrated in tiny particles called corpuscles. He further assumed that corpuscles of light were mass less

elastic particles. With his understanding of mechanics, he could come up with a simple model of refraction

and refraction. It is a common observation that a ball bouncing from a smooth plane surface obeys the laws

of reflection.

In order to explain the phenomenon of refraction, Newton postulated that the speed of corpuscles in a similar

manner.

In field of Optics, Newton- the experimenter was greater than Newton- the theorist. He himself observed

many phenomena, which were difficult to understand in terms of particle nature of light. For example, the

colours observed due to a thin film of oil on water. Property of partial reflection of light is yet some another

such example. Newton argued that some of the corpuscles, which fall on the water, get reflected and some

get transmitted. An incoming wave can be divided into two weaker waves at the boundary between air and

water.

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INTRODUCTION

The basic problem which I saw there was that student’s face problem regarding the differences between the

spherical mirrors (curved mirror). They unable to remember the ray diagrams related to Curved mirrors,

even they feel difficulty related to differences between the concave and convex mirrors.

The challenges for this problem was to make student aware of the real life examples related to spherical

mirrors as well as the remembrance of ray diagram related to spherical mirror.

Therefore, it was really a problematic situation to teach them the differences between the concave and

convex mirrors, reflection of light by spherical mirrors, sign convention, focal length of spherical mirrors.

Some Specific Questions Which Are Relevant To Explain The Need Of Research:

i) Why it is necessary to know the differences of the curved mirror?

ii) Why the two curved mirrors are unique at their own aspects?

iii) Is there any simple way to remember the ray diagrams related to curved mirrors?

iv) Why these curved mirrors are important in day to life?

v) Why there is need to learn these mirrors?

vi) How these ray diagrams have unique Characteristics?

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Research Setting

I completed my Action Research at TEJAS VIDYALAYA. Tejas Vidyalaya is an English medium School,

managed by Uday Education Society. Tejas Vidyalaya believes in no compromise, complete education for

children in school. Tejas is proud to provide the umbrella of an all-encompassing education to students.

The Aim of the school is to “The Wonder of Learning is that, NO one can take it away from you”.

In the first visit, I met with the coordinator of Secondary Section Mansi Mam. She asked about my method

subject and allotted me standard 7th B for science and mathematics and sent me to take the topic from the

respective class teacher. I met with Ms. Sumita Mam (science Teacher) and Ms. Neelum Mam (Mathematics

Teacher), both gave me topics of the chapter That is, Waste Water Management and Congruent Triangles

respectively.

Then I discussed, my action research related problem with the Science Teacher. She told me students

generally face problem related to SPHERICAL MIRRORS (RAY DIAGRAMS). She explained very nicely

that students are lacking in memorization of ray diagram rules and differences between the curved mirrors.

So I decided that I will do my best to solve this problem and enable the learners to adopt the simplest way to

learn the ray diagrams and main features of curved mirrors.

To begin the research, first, I talked to students what are the problems you generally face regarding the

science subjects, which of topic you all feel difficulty to memorize, to learn, to differentiate etc.

Then they discussed that they face difficulty regarding the differences between the differences regarding

concave and convex mirrors and their sign conventions and ray diagrams.

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Review of related literature

Reflection of light by spherical Mirrors

We are familiar with the Law of Reflection. The angle of reflection (i.e. the angle between reflected ray and

the normal to the reflecting surface or the mirror) equals the angle of incidence (angle between incident ray

and the normal). Also that the incident ray, reflected ray and the reflecting surface at the point of incidence

lie in the same plane. These laws are valid at each point on any reflecting surface whether plane or curved.

We shall discuss to the special case of curved surfaces, that is, spherical surfaces. The normal in this case is

to be taken as normal to the tangent to surface at the point of incidence. That is, the normal is along the

radius, the line joining the centre of curvature of the mirror to the point of incidence.

Curved Mirrors and Ray Diagrams

The everyday flat type of mirror is called a “plane mirror”. All light travelling straight towards this mirror

reflects right back at you. As such, you always get an image that is an exact duplicate of you. Remember,

MIRRORS REFLECT LIGHT, so it bounces off them. This may seem silly in that we already know that,

but as we talk of more optical instruments it’s something you should keep in mind.

Curved mirrors are not flat and therefore light reflects differently off them making different types of images.

There are two types of curved mirrors.

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A concave mirror is a curved mirror with the reflecting surface on the inside of the curve. The point C is

the centre of curvature and the distance between C and the vertex A is the radius of curvature, R.

Halfway between C and A is F, the focal point or principal focus. The focal length, f = R/2.

A convex mirror is a curved mirror with reflecting surface on the outside of the curve. The point C is the

centre of curvature and the distance between C and the vertex A is the radius of curvature, R. Halfway

between C and A is F, the focal point or principal focus. The focal length, f = R/2.

According to this convention, all distances are measured from the pole of the mirror or the optical centre of

the lens. The distances measured in the same direction as the incident light are taken as positive and those

measured in the direction opposite to the direction of incident light are taken a negative. The heights

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measured upwards with respect to x-axis and normal to the principal axis (x- axis) of the mirror/ lens is taken

as positive. The heights measured downward are taken as negative.

With a common accepted convention, it turns out that a single formula for spherical mirrors and a single

formula for spherical lenses can handle all different cases.

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Students will be able to memorize the ray diagrams of concave and convex mirror.

How do I memorize The Ray diagrams of Spherical mirrors/ lenses:

The aim of this research is to enable the students to identify the differences between the concave and convex

mirror.

Concave mirrors: were silvered on the inside of the sphere.

Convex mirrors: were silvered on the outside of the sphere.

In order to understand spherical mirrors, it is important to understand and learn some terminology.

Principal axis: If a concave mirror is thought of as being a slice of a sphere, then there would be a line

passing through the center of the sphere and attaching to the mirror in the exact center of the mirror.

Center of curvature(C): The point in the center of sphere from which the mirror was sliced.

Vertex (A): The point on the mirror's surface where the principal axis meets the mirror. The vertex is the

geometric center of the mirror.

Focal point (F): Midway between the vertex and the center of curvature

Radius of curvature(R): The distance from the vertex (A) to the center of curvature (C). The radius of

curvature is the radius of the sphere from which the mirror was cut.

Focal length (f): Finally, the distance from the mirror to the focal point. Since the focal point is the midpoint

of the line segment adjoining the vertex and the center of curvature, the focal length would be one-half the

radius of curvature.

Real Image: When a real image is formed, it still appears to an observer as though light is diverging from

the real image location. Only in the case of a real image, light is actually passing through the image location.

Such images are formed on the same side of the mirror as the object and light passes through the actual

image location.

Virtual Image: Virtual images are images which are formed in locations where light does not actually reach.

Light does not actually pass through the location on the other side of the mirror; it only appears to an

observer as though the light were coming from this position. Whenever a mirror (whether a plane mirror or

otherwise) creates an image which is virtual, it will be located behind the mirror where light does not really

pass.

Concave Mirrors

Two simple rules of reflection for concave mirrors:

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• Any incident ray travelling parallel to the principal axis on the way to the mirror will pass through the

focal point upon reflection.

• Any incident ray passing through the focal point on the way to the mirror will travel parallel to the

principal axis upon reflection.

These two rules of reflection are illustrated in the diagram below.

A ray travelling parallel to the principal axis will reflect through the focal point.

A ray travelling through the focal point will reflect parallel to the principal axis.

Image Characteristics for Concave Mirrors

The best means of summarizing this relationship is to divide the possible object locations into five general

areas or points:

Case 1: the object is located beyond the center of curvature (C)

Case 2: the object is located at the center of curvature (C)

Case 3: the object is located between the center of curvature (C) and the focal point (F)

Case 4: the object is located at the focal point (F)

Case 5: the object is located in front of the focal point (F)

Case 1: The object is located beyond C

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When the object is located at a location beyond the center of curvature:

The image will be somewhere between the center of curvature and the focal point.

• The image will be inverted. (i.e. if the object is right-side up, then the image is upside down).

• The image is reduced in size; in other words, the image dimensions are smaller than the object

dimensions. Therefore, the magnification is a number less than 1.

• The image is a real image. Light rays actually converge at the image location. If a sheet of paper was

placed at the image location, the actual replica of the object would appear projected upon the sheet of

paper.

Case 2: The object is located at C

When the object is located at the center of curvature:

• The image will be at the center of curvature.

• The image will be inverted (i.e., a right-side-up object results in an upside-down image).

The image dimensions are equal to the object dimensions. A six-foot tall person would have an

image which is six feet tall; the magnification is exactly 1.

• The image is real.

Case 3: The object is located between C and F

When the object is located in front of the center of curvature:

• The image will be beyond the center of curvature.

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• The image will be inverted.

• The image dimensions are larger than the object dimensions. A six-foot tall person would have an

image which is larger than six feet tall; the magnification is greater than 1.

• The image is real

Case 4: The object is located at F

When the object is located at the focal point:

• No image is formed (or the image will be at infinity).

• The reflected rays either converge or diverge. After reflecting, the light rays are travelling parallel to

each other and cannot produce an image.

• If we assume that an image is formed at infinity then:

o The image will be inverted.

o The image dimensions are larger than the object dimensions.

o The magnification is greater than 1.

o The image is a real image.

Case 5: The object is located in front of F

When the object is located in front of F:

• The image will be on the opposite side of the mirror, behind the mirror.

• The image will upright (not inverted).

• The image is enlarged; the magnification is greater than 1.

• The image is virtual. Light rays diverge upon reflection; for this reason, the image location can only be

found by extending the reflected rays backwards beyond the mirror. The point of their intersection is

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the virtual image location. It would appear to any observer as though light from the object were

diverging from this location. Any attempt to project such an image upon a sheet of paper would fail

since light does not actually pass through the image location.

Summary of Different forms of image in

Concave mirrors

Nine different object locations are drawn and labelled with a number; the corresponding image locations are

drawn in Black and labelled with the identical number.

Concave mirrors can produce both real and virtual images.

Convex Mirrors

Two simple rules of reflection for convex mirrors:

• Any incident ray travelling parallel to the principal axis on the way to a convex mirror will reflect in a

manner that its extension will pass through the focal point.

• Any incident ray travelling towards a convex mirror such that its extension passes through the focal

point will reflect and travel parallel to the principal axis.

Image Characteristics for Convex Mirrors

Unlike concave mirrors, convex mirrors always produce images which share same characteristics. The

location of the object does not affect the characteristics of the image. So, the characteristics of the images

formed by convex mirrors are easily predictable.

The diagrams are shown below.

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The diagrams above shows that in each case, the image is

The image will be located behind the convex mirror.

A virtual image will be formed. Light rays diverge upon reflection; for this reason, the image location can

only be found by extending the reflected rays backwards beyond the mirror. The point of their intersection is

the virtual image location. It would appear to any observer as though light from the object were diverging

from this location. Any attempt to project such an image upon a sheet of paper would fail since light does

not actually pass through the image location.

The image will be upright.

The image will be smaller than the object. So, the magnification will be smaller than 1.

The image is always formed between the focal point and mirror.

Summary of Different forms of image in

Convex mirrors

The diagram below shows seven different object locations (drawn and labelled in gray) and their

corresponding image locations (drawn and labelled in black).

Convex mirror can only form an upright, and virtual image.

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Problem Solving

Front, or Real side

p and q positive

Incident light

Reflected light

f is always positive for concave mirror.

f is always negative for convex mirror.

p and q are positive if they are in front of the mirror.

p and q are negative if they are in back of the mirror.

Students will be able learn the short-cut method related to concave and convex mirror.

A short-cut Method to Learn converging and diverging:

CONVERGING

1. The object is located beyond the radius of curvature (R) – SIR (smaller, inverted, real)

2. The object is located at R- SSIR(same size, inverted, real)

3. The object is located between R and F- LIR (larger, inverted, real)

4. The object is located at F – no image is formed

5. The object is located between F and the mirror – LUV (larger, upright, virtual)

DIVERGING

1. Always SUV (smaller, upright, virtual).

Back or Virtual side

p and q negative

No light

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I'm having a lot of trouble with ray diagrams (lenses). what's the easiest way

to understand them

i understand the whole convex lenses and concave mirrors have the same properties and are both converging

(positive focal length) while concave lenses and convex mirrors are both diverging (negative focal length)

and that real and inverted images are always associated with each other and usually virtual and upright ones

are. I have a lot of trouble with diagrams and stuff like seeing what happens to the image at the focal point,

beyond the focal point and determining whether or not the images are magnified or what? How is this easily

done? is there something simple that I could memorize so i dont have to draw the things out?

honestly, this is one of the few topics I recommend just memorizing the rules. It mostly shows up as a

discrete with a very common answer structure.. so you can get away with just knowing the rules/tricks and

not fully understanding ray diagrams. Of course, this can backfire if you get an optics passage but even then,

you should be okay.

converging:

1) the object is located beyond the radius of curvature (R)- SIR (smaller, inverted, real)

2) the object is located at R- SSIR (same size, inverted, real)

3) the object is located between R and F- LIR (larger, inverted, real)

4) the object is located at F- no image is formed

5) the object is located between F and the mirror- LUV (larger, upright, virtual)

diverging:

always SUV (smaller, upright, virtual)

from there, you just need to know the sign conventions so you can figure out which side of the mirror/lens

the object/image is on, etc. You can also relate the size relationship to the image location (larger = farther

out, etc.).

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That really should take care of 90% of optics questions and is a quick memorization. It's best to memorize as

little as possible but here is a situation where I'd say go for it.

Jepstein30, 12.30.13

1. BerkReviewTeachCompany Rep & Bad SingerExhibitor

Jepstein hit the nail on the head. To see that list with pictures tossed in, assuming you have access to BR

books, look at pages 247-250. It's that exact list with the ray diagrams (which are obsolete if you use the

chart).

2. Jepstein30

exactly where I picked it up from originally

makes it easy.

Diverging SUV

Converging SIR -> LUV

Students will be able to differentiate between concave and convex mirror.

CONCAVE MIRROR CONVEX MIRROR

Structure A concave mirror is a spherical mirror in

which the reflecting surface and the center of

curvature fall on the same side of the mirror.

In other words, if the mirror coating lies

outside of the spherical surface, then it is

known as a concave mirror.

A convex mirror is a spherical

mirror in which the reflecting

surface and the center of curvature

lie on the opposite sides of the

mirror. In other words, if the

mirror coating lies in the inside of

the spherical surface, then it is

known as a convex mirror.

Other name Converging Mirror Diverging Mirror

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Image projection Can be projected on a screen Cannot be projected on a screen

Meaning Concave means “hollowed or rounded”. Convex means “curved or rounded

like the outside of a sphere or

circle”.

Image

(C stands for center of

curvature, F for focal

point and V for vertex

Position of object (infinity) Position of

Image (At F) Character of Image (Real,

zero size)

Position of object (between infinity and

C) Position of Image (Between F and

C) Character of Image (real, inverted,

diminished)

Position of object (AT C) Character of

Image (Real, inverted, same size)

Position of object (Between C and F)

Position of Image (Between C and

infinity). Character of Image (Real,

inverted, magnified)

Position of object (Between F and V)

Position of Image (From –infinity to V)

Character of Image (Virtual, upright,

magnified)

Position of object (AT V) Position of

Image (At V) Character of Image

(Virtual, upright, same size)

Position of object (infinity)

Position of Image (At

F) Character of Image

(Virtual, zero size)

Position of object (between

infinity and V) Position of

Image (Between F and

V) Character of Image

(Virtual, upright,

Diminished)

Position of object (AT V)

Position of Image (At V)

Character of Image (Virtual,

upright, same size)

Real life examples of Spherical mirror/curved mirror:-

Concave mirrors

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1. Headlights of car- the source of light is placed at the focus of the concave reflector

2. Dentist mirror- focus of light on the tooth to be examined

3. Make-up mirror- enlarges the image to be easier to see

Convex mirrors

1. Side view mirror- allows the driver to see more objects and a wider view of what’s behind.

2. Security mirrors-used in malls, convenience stores, and supermarkets to view a large portion of

people

3. Camera phone- helps to aim correctly when taking a self-portrait.

What are the uses of lenses?

1. Magnifying glass – Convex lens.

2. To correct eye defects –people who can not see far off objects clearly wear Concave lens.

People who cannot see nearby object clearly wear Convex lens.

3. lenses are also used in Microscope, Telescope etc.

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(i) To enable the learner to identify and implement and memorize the concept of spherical

mirrors and differences between the concave and convex mirrors.

(ii) To enable the learner to remember the ray diagram of concave and convex mirrors.

(iii) To enable the learner to establish the real life examples of spherical mirror.

PARTICIPANTS

The main participants of this action research were the students of class 7 th of Tejas vidyalaya.

When I went there for practice teaching and received the topic from science. On the 2-3 day in class when I

started to teach, they told me just like this chapter can you please solve our queries related to Spherical

Mirrors (lenses). They also have problem regarding examples of spherical mirrors and lenses and why these

mirrors are different from the plane mirrors.

So, I decided to give them some tricks, ideas related to spherical mirrors. For this, I showed them videos,

images, animation and Power Point presentation. I showed them one video, 6 cases or rule of concave mirror

related pictures and based on that I showed them animation of ray diagrams and finally to conclude

everything I showed them one presentation.

In this way they become the part of this research.

DATA COLLECTION

For this, I first of all used a questionnaire for pre-test and analyse their prior knowledge regarding the

reflection and spherical mirrors. Then I set my strategy according to that, I give them some objectives and

some ray diagrams and some definitions related to Topic. In this way after some time they won’t get confuse

with the name and will remember that for longer period of time.

After a week I conducted the post- test through the Questionnaire to check how much they improved. I gave

them the hints whenever I feel that they are confused.

PROCESS OF DATA COLLECTION

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To collect the data I conducted pre and post- test, I taught them the tricks, the concept during the class time

and also gave them some notes related to content. So, that they can go through that and try to remember the

rules, concept and ideas which I taught them. I gave them full freedom to ask anything (Questions) related to

the topic. I make them to come on board and try to make the ray diagrams which confuse them more. So, In

this way I clarify their doubts by providing them a good content knowledge, small shortcuts, tricks etc.

.

RESEARCH FINDING

It was really a tough task to create interest to create among the student that chemistry is a very interesting

subject and after understanding its pros and cons it will really enhance their knowledge related to science.

When I started to teach the tricks, the theory part, the ray diagram many of the students were confused, but

one thing I like that was whenever they feel difficulty they immediately ask Question and solve their queries,

though still while learning they were confused, because many of the things they have to imagine and they

cannot see them in reality. But I tried to show them example of spherical mirrors and they can coorelate that

all things with their day to day life experiences. I feel lucky that i get this kind of experiences in my life and

I am able to complete my action research in a good and meaningful way.

(i) A majority of students find science as an tough subject but they also feel that it is base of

their life and they need to score more in that subject.

(ii) A majority of students helps their friends to learn the tricks and helped teacher also were

they and their friends feel difficulty.

(iii) The main reason is that they doesn’t able to correlate the ray diagrams to real life

examples and rules related to ray diagrams they find that these are tough.

CONCLUSION

Reflection of light contains subtopic spherical mirror and lenses. These are the chapter which requires more

imagination than the reality and this is reason that a child does not able to learn this kind of chapter. Then,

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this kind of chapter contains so many rules, formulas (though it not for class 7th), ray figures, differences etc.

That a child feels boring and tough to remember. For this kind of topics a teacher can show demonstrations,

videos, pictures etc. These all can help the children to take interest in these kinds of topics. When a child feel

difficulty to learn a subject, it automatically hates that subject so, a teacher is one who take extra care for this

kind topics and help the children’s to understand such kind of topics in a easiest way.

I personally feel that this chapter is tough for students if we show them experiments, real life example

related videos, pictures help the children out with this kind of problem. I tried whatever I can do for this age

group and help them and make them understood this kind of chapter.

Thus, I can say, combine efforts of student interest and teacher’s ideas can solve anything. Innovative and

enthusiastic efforts are essential to enhance the performance.

BIBLIOGRAPHY AND URLS USED TO MAKE THIS ACTION RESEARCH:-

http://micro.magnet.fsu.edu/primer/java/mirrors/concavemirrors/

http://asq.org/learn-about-quality/problem-solving/overview/overview.html

http://www.studygs.net/problem/problemsolvingv1.htm

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http://www.colorado.edu/physics/phys1230/phys1230_fa01/topic18.html

http://micro.magnet.fsu.edu/optics/lightandcolor/reflection.html

http://www.universetoday.com/45228/convex-mirror/

http://farside.ph.utexas.edu/teaching/302l/lectures/node136.html

https://www.youtube.com/watch?v=aV5X9Ee7Rnc

http://dev.physicslab.org/Document.aspx?doctype=3&filename=GeometricOptics_SphericalMirrors.x

ml

https://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=8&ved=0CEcQFjAH&url=htt

p%3A%2F%2Fwww.physics.utah.edu%2F~woolf%2F3220_deford%2Fsphericalmirrors.pdf&ei=QMj

kVJaQCM2HuATUg4KQCg&usg=AFQjCNEev72rGUigtM-96wmuePYgDxXyzw

https://secure.lcisd.org/.../Ray%20Diagrams-Spherical%20Mirrors.pdf

Science text book class 7th NCERT and GSEB Board.

Pictures taken from google images site.

1.Out of convex mirror and concave mirror, whose focus is situated behind the mirror?

Ans: The focus of convex mirror is situated behind it.

2. For what position of an object, a concave mirror forms an enlarged virtual image?

Ans: Object between pole (P) and focus (F) of the concave mirror.

4. A ray of light falls on a mirror normally. What are the values of angle of incidence and the angle of reflection?

Ans: Both angle of incidence and the angle of reflection are zero.

5. What is the focal length of a plane mirror?

Ans: Infinite.

SQA

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Q3. What are the laws of reflection?

Ans. Angle of incidence is equal to angle of reflection.Incedent, reflected ray & the normal lie on the same plane.

Q4. What is the nature of image formed in a plane mirror?

Ans. Virtual, erect, same image, laterally Inverted (left appears right & vice versa), at same distance from the mirror as the object.

Q6. What type of mirror – the inner surfact of the Spoon acts as and the outer surface of the spoon acts as ?

Ans. Inner surface of the spoon acts as Concave mirror and the outer surface of the spoon acts as concave mirror.

Q7. Which concave mirror called a converging mirror and a convex mirror called a diverging mirror?

Ans. Concave mirror is called a converging mirror because parallel rays of light fall on the mirror they Converge at a point called

focus.

Convex mirror is called a diverging mirror because parallel rays of light fall on it they diverge after reflection.

Q13. What is a lens?

Ans. A piece of transparent material bound by curved surfaces.

Q14. Difference between a convex lens & a Concave lens?

CONVEX LENS

1. It is Thick at the Centre and thinner at edges

2. It is called converging lens

CONCAVE LENS

1. It is thin at the center and thicker at edges

2. It is called diverging lens.

Q19. How is the rainbow formed?

Ans. Rainbow is formed after rainfall when Sun Shines. When sunlight passes through suspended raindrops it is split into seve n

colours “VIBGYOR’.

Q20. Where else you can see seven colours of sunlight?

Ans. You can see Seven colours of Sunlight when it falls over Soap bubbles, oil films, Shiny surfaces of CD etc.

Q 21. State the characteristics of the image formed by a plane mirror.

Ans:

1. Image is Virtual

2. It is behind the mirror

3. Image is erect (means not inverted)

4. Image is of same size as the object

5. Image is at same distance from the mirror as the object is from the mirror.

Q22. Fill in the blanks

a. An image that cannot be obtained on a screen is called --------

b. Image formed by a convex ------------- is always virtual and smaller in size.

c. An image formed by a ------------- mirror is always of the same size as that of the object.

d. An image which can be obtained on a screen is called a ----------- image.

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e. An image formed by a concave ------------ cannot be obtained on a screen.

Answers: a) virtual image b) convex mirror c) planed) real e) concave lens

When the object is located at the focal point what kind of image it will form in case of concave mirror?

When the object is located in front of the center of curvature what kind of image it will form in case of concave mirror?

In which mirror this kind of image will be form:

The image will be upright.

The image will be smaller than the object. So, the magnification will be smaller than 1.

The image is always formed between the focal point and mirror.

Make the ray diagram with labelling?

1. When the object is located at the focal point:

• No image is formed (or the image will be at infinity).

• The reflected rays either converge or diverge. After reflecting, the light rays are travelling parallel to each other and cannot produce an

image.

• If we assume that an image is formed at infinity then:

o The image will be inverted.

o The image dimensions are larger than the object dimensions.

o The magnification is greater than 1.

o The image is a real image.

2.When the object is located in front of the center of curvature:

The image will be beyond the center of curvature.

• The image will be inverted.

• The image dimensions are larger than the object dimensions. A six-foot tall person would have an image which is larger than six feet tall;

the magnification is greater than 1.

• The image is real

Questionnaire For PRE-TEST On SPERICAL MIRRORS

1. Out of convex mirror and concave mirror, whose focus is situated behind the mirror?

________________________________________________________________________

2. For what position of an object, a concave mirror forms an enlarged virtual image?

__________________________________________________________________________

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3. A ray of light falls on a mirror normally. What are the values of angle of incidence and the angle of

reflection?

___________________________________________________________________________

4. What is the focal length of a plane mirror?

____________________________________________________________________________

5. What are the laws of reflection?

_______________________________________________________________________________________

_______________________________________________________________________________________

6. What is the nature of image formed in a plane mirror?

_______________________________________________________________________________________

_______________________________________________________________________________________

7. What type of mirror – the inner surfact of the Spoon acts as and the outer surface of the spoon acts

as ?

_______________________________________________________________________________________

_______________________________________________________________________________________

______________________________________________________________________________________

8. Which concave mirror called a converging mirror and a convex mirror called a diverging mirror?

_______________________________________________________________________________________

_______________________________________________________________________________________

_______________________________________________________________________________________

9. What is a lens?

_______________________________________________________________________________________

_______________________________________________________________________________________

_______________________________________________________________________________________

10. How is the rainbow formed?

_______________________________________________________________________________________

_______________________________________________________________________________________

11. Where else you can see seven colours of sunlight?

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_______________________________________________________________________________________

______________________________________________________________________________________

12. State the characteristics of the image formed by a plane mirror.

_______________________________________________________________________________________

_______________________________________________________________________________________

13. Fill in the blanks

a. An image that cannot be obtained on a screen is called --------

b. Image formed by a convex ------------- is always virtual and smaller in size.

c. An image formed by a ------------- mirror is always of the same size as that of the object.

d. An image which can be obtained on a screen is called a ----------- image.

e. An image formed by a concave ------------ cannot be obtained on a screen.

14. When the object is located at the focal point what kind of image it will form in case of concave mirror?

15. When the object is located in front of the center of curvature what kind of image it will form in case of

concave mirror?

16. In which mirror this kind of image will be form:

a. The image will be upright.

b. The image will be smaller than the object. So, the magnification will be smaller than 1.

c. The image is always formed between the focal point and mirror.

Make the ray diagram with labelling?

Questionnaire For Post-TEST On SPERICAL MIRRORS

1. Out of convex mirror and concave mirror, whose focus is situated behind the mirror?

________________________________________________________________________

2. For what position of an object, a concave mirror forms an enlarged virtual image?

__________________________________________________________________________

30

3. A ray of light falls on a mirror normally. What are the values of angle of incidence and the angle of

reflection?

___________________________________________________________________________

4. What is the focal length of a plane mirror?

____________________________________________________________________________

5. What are the laws of reflection?

_______________________________________________________________________________________

_______________________________________________________________________________________

6. What is the nature of image formed in a plane mirror?

_______________________________________________________________________________________

_______________________________________________________________________________________

7. What type of mirror – the inner surfact of the Spoon acts as and the outer surface of the spoon acts

as ?

_______________________________________________________________________________________

_______________________________________________________________________________________

_______________________________________________________________________________________

8. Which concave mirror called a converging mirror and a convex mirror called a diverging mirror?

_______________________________________________________________________________________

_______________________________________________________________________________________

_______________________________________________________________________________________

9. What is a lens?

_______________________________________________________________________________________

_______________________________________________________________________________________

_______________________________________________________________________________________

10. How is the rainbow formed?

_______________________________________________________________________________________

_______________________________________________________________________________________

11. Where else you can see seven colours of sunlight?

31

_______________________________________________________________________________________

______________________________________________________________________________________

12. State the characteristics of the image formed by a plane mirror.

_______________________________________________________________________________________

_______________________________________________________________________________________

13. Fill in the blanks

a. An image that cannot be obtained on a screen is called --------

b. Image formed by a convex ------------- is always virtual and smaller in size.

c. An image formed by a ------------- mirror is always of the same size as that of the object.

d. An image which can be obtained on a screen is called a ----------- image.

e. An image formed by a concave ------------ cannot be obtained on a screen.

14. When the object is located at the focal point what kind of image it will form in case of concave

mirror?

15. When the object is located in front of the center of curvature what kind of image it will form in

case of concave mirror?

16. In which mirror this kind of image will be form:

a. The image will be upright.

b. The image will be smaller than the object. So, the magnification will be smaller than 1.

c. The image is always formed between the focal point and mirror.

Make the ray diagram with labelling?