KEEP IT UP COACHING POINT
“Obstacles are what you see when you take your eyes off the goal.”
LIGHT - REFLECTION AND REFRACTION
OPTICS:-- The branch of science in which we study various phenomenon and characteristics of light is
called optics.
LIGHT:-- It is that invisible source of energy which enables us to see objects.
Characteristics of Light.
1. Light is an energy.
2. It propagates in the form of wave.
3. Light waves are electromagnetic waves i.e. along with light, waves produce electrical waves as well as
magnetic waves and all these three waves are perpendicular to each other.
4. Light waves always propagate in straight path.
5. The velocity of light in air as well as in vacuum is 3×108m.sec-1.
6. Light is a matter and smallest unit of light is called Photon, name proposed by Newton.
7. Hence, light has got dual nature i.e. wave nature as well as particulate nature.
8. Light shows many properties like reflection, refraction, dispersion, rarefaction, interference etc.
Important Definitions
1) Luminous Objects: → The objects that emit their own light are called Luminous Objects eg. Sun, Star
etc.
2) Non-Luminous Objects→ The objects that do not emit their own light rather they reflect the light of
luminous objects eg Moon, Humans etc
3) Optical Medium: Anything through which light energy passes partially or completely is called Optical
Medium.
They are of two types:--→
Homogenous Optical Medium: → The Optical Medium which are uniform through out are called
Homogenous Optical Medium .eg Diamond, glass Pure H2O, vacuum.
Heterogeneous Optical Medium→ The optical medium which are not uniform through out are called
Heterogeneous Optical Medium eg: Atmosphere (air) fog, mist clouds etc,
Note: → Further medium classification includes transparent, translucent and opaque materials.
4) Ray of Light: → The straight line along which light propagates is called Ray of Light.
5) Beam of Light: → Collection or bundle of many light rays is called Beam of Light.
Question Bank
Q1) a) Define light.
b) List 4 characteristics of light.
c) Light waves are electromagnetic waves. Explain.
d) Light has dual nature. Explain.
e) What is the particle of light called?
f) What is the velocity of light in air/ vacuum?
Q2) Definitions:→ Light, Luminous Object, Non-Luminous Objects, Optical Medium, Image, Plane
Mirror, Spherical Mirror, Lens, Reflection, Refraction.
Q3) a) Define an image.
b) Differentiate real v/s virtual image.
( Not to Miss) Q4)a) What is a plane mirror?
b) Draw ray diagram of image formation by a plane mirror.
c) List 4 characteristics of the image formed by a plane mirror.
d) Why is one side of a glass sheet polished with silver to form a plane mirror?
e) Why is silver coated with red paint?
C- 162 Govindpura Kardhani, Kalwar Road, Jhotwara, Jaipur -302012
Contact : 8890497070, 9649978593, 9782830493
, KEEP IT UP COACHING POINT
“Obstacles are what you see when you take your eyes off the goal.”
Q5) a) Define reflection.
b) Draw a ray diagram showing incident ray, reflected ray, normal, angle of incidence and angle of
reflection by a plane mirror.
c) In the following figure find angle of reflection.
d) State 2 laws of reflection.
e) How many minimum reflected or refracted rays should meet at a point actually or apparently to
form image of object after diverging from this object?
Ans 3) a) Image is that point where two or more reflected rays actually or apparently meet after diverging
from an object.
b)
Real Image Inverted Image
1) Actual meeting of two or more reflected 1) Apparent meeting of two or more
or refracted rays takes place. reflected or refracted rays takes place.
2) Can be taken on screen 2) Can’t be taken on screen.
3) Real image is always inverted image. 3) Virtual image is always erect image.
Ans4) a) It is a plane glass sheet whose one surface is polished with silver which is coated with red oxide
paint.
b)
c) 1) Image distance is always equal to object distance from mirror.
2) Size of image is always equal to size of object
3) It is virtual and cannot be taken on the screen.
4) The image formed by a plane mirror is behind the mirror.
5) The image formed in the plane mirror is laterally inverted i.e., right portion of object becomes left and left
portion becomes right.
6) The image formed by a plane mirror is erect.
7) Apparent meeting of reflected rays takes place.
d) i) Silver is a very conductor of light.
ii) It is also a very good reflector of light
Due to above two properties, silver is polished on one side of plane glass sheet to form a plane mirror.
C- 162 Govindpura Kardhani, Kalwar Road, Jhotwara, Jaipur -302012
Contact : 8890497070, 9649978593, 9782830493
, KEEP IT UP COACHING POINT
“Obstacles are what you see when you take your eyes off the goal.”
e) i) Silver is scratch able metal, scratches of its own.
ii) To prevent this, it s coated with red oxide paint which also symbolizes danger because glass can cause
accidents if not handled carefully.
Uses of Plane Mirror
1) It is used in solar cookers.
2) Mirrors of dressing tables, saloons and bathrooms are plane mirrors.
3) They are used in show rooms.
4) They are fitted at blind turns of some busy roads so that drivers can see the vehicles coming from the other
side.
5) They are used to make periscope.
Reflection Of Light
Phenomenon of sending back of light rays by a surface in the same medium from which it was travelling after
striking is called Reflection. It is of two types.
Characters Regular Irregular
Reflecting Surface Smooth and polished Rough and bumpy
Image Formed Clear Blur
Example
Laws of Reflection
1) Angle of Incidence is always equal to angle of reflection.
2) Normal, incident ray and reflected ray always lie on the same plane.
3) The point where incident ray strikes the plane mirror is called point of incidence. Normal is the imaginary
line perpendicular to point of incidence.
∠1= Glance Angle of incidence
∠2= Glance Angle of reflection
SPHERICAL MIRROR
Q6) a) Define Spherical Mirror.
b) How many kinds of spherical mirrors are there?
C- 162 Govindpura Kardhani, Kalwar Road, Jhotwara, Jaipur -302012
Contact : 8890497070, 9649978593, 9782830493
“Obstacles are what you see when you take your eyes off the goal.”
LIGHT - REFLECTION AND REFRACTION
OPTICS:-- The branch of science in which we study various phenomenon and characteristics of light is
called optics.
LIGHT:-- It is that invisible source of energy which enables us to see objects.
Characteristics of Light.
1. Light is an energy.
2. It propagates in the form of wave.
3. Light waves are electromagnetic waves i.e. along with light, waves produce electrical waves as well as
magnetic waves and all these three waves are perpendicular to each other.
4. Light waves always propagate in straight path.
5. The velocity of light in air as well as in vacuum is 3×108m.sec-1.
6. Light is a matter and smallest unit of light is called Photon, name proposed by Newton.
7. Hence, light has got dual nature i.e. wave nature as well as particulate nature.
8. Light shows many properties like reflection, refraction, dispersion, rarefaction, interference etc.
Important Definitions
1) Luminous Objects: → The objects that emit their own light are called Luminous Objects eg. Sun, Star
etc.
2) Non-Luminous Objects→ The objects that do not emit their own light rather they reflect the light of
luminous objects eg Moon, Humans etc
3) Optical Medium: Anything through which light energy passes partially or completely is called Optical
Medium.
They are of two types:--→
Homogenous Optical Medium: → The Optical Medium which are uniform through out are called
Homogenous Optical Medium .eg Diamond, glass Pure H2O, vacuum.
Heterogeneous Optical Medium→ The optical medium which are not uniform through out are called
Heterogeneous Optical Medium eg: Atmosphere (air) fog, mist clouds etc,
Note: → Further medium classification includes transparent, translucent and opaque materials.
4) Ray of Light: → The straight line along which light propagates is called Ray of Light.
5) Beam of Light: → Collection or bundle of many light rays is called Beam of Light.
Question Bank
Q1) a) Define light.
b) List 4 characteristics of light.
c) Light waves are electromagnetic waves. Explain.
d) Light has dual nature. Explain.
e) What is the particle of light called?
f) What is the velocity of light in air/ vacuum?
Q2) Definitions:→ Light, Luminous Object, Non-Luminous Objects, Optical Medium, Image, Plane
Mirror, Spherical Mirror, Lens, Reflection, Refraction.
Q3) a) Define an image.
b) Differentiate real v/s virtual image.
( Not to Miss) Q4)a) What is a plane mirror?
b) Draw ray diagram of image formation by a plane mirror.
c) List 4 characteristics of the image formed by a plane mirror.
d) Why is one side of a glass sheet polished with silver to form a plane mirror?
e) Why is silver coated with red paint?
C- 162 Govindpura Kardhani, Kalwar Road, Jhotwara, Jaipur -302012
Contact : 8890497070, 9649978593, 9782830493
, KEEP IT UP COACHING POINT
“Obstacles are what you see when you take your eyes off the goal.”
Q5) a) Define reflection.
b) Draw a ray diagram showing incident ray, reflected ray, normal, angle of incidence and angle of
reflection by a plane mirror.
c) In the following figure find angle of reflection.
d) State 2 laws of reflection.
e) How many minimum reflected or refracted rays should meet at a point actually or apparently to
form image of object after diverging from this object?
Ans 3) a) Image is that point where two or more reflected rays actually or apparently meet after diverging
from an object.
b)
Real Image Inverted Image
1) Actual meeting of two or more reflected 1) Apparent meeting of two or more
or refracted rays takes place. reflected or refracted rays takes place.
2) Can be taken on screen 2) Can’t be taken on screen.
3) Real image is always inverted image. 3) Virtual image is always erect image.
Ans4) a) It is a plane glass sheet whose one surface is polished with silver which is coated with red oxide
paint.
b)
c) 1) Image distance is always equal to object distance from mirror.
2) Size of image is always equal to size of object
3) It is virtual and cannot be taken on the screen.
4) The image formed by a plane mirror is behind the mirror.
5) The image formed in the plane mirror is laterally inverted i.e., right portion of object becomes left and left
portion becomes right.
6) The image formed by a plane mirror is erect.
7) Apparent meeting of reflected rays takes place.
d) i) Silver is a very conductor of light.
ii) It is also a very good reflector of light
Due to above two properties, silver is polished on one side of plane glass sheet to form a plane mirror.
C- 162 Govindpura Kardhani, Kalwar Road, Jhotwara, Jaipur -302012
Contact : 8890497070, 9649978593, 9782830493
, KEEP IT UP COACHING POINT
“Obstacles are what you see when you take your eyes off the goal.”
e) i) Silver is scratch able metal, scratches of its own.
ii) To prevent this, it s coated with red oxide paint which also symbolizes danger because glass can cause
accidents if not handled carefully.
Uses of Plane Mirror
1) It is used in solar cookers.
2) Mirrors of dressing tables, saloons and bathrooms are plane mirrors.
3) They are used in show rooms.
4) They are fitted at blind turns of some busy roads so that drivers can see the vehicles coming from the other
side.
5) They are used to make periscope.
Reflection Of Light
Phenomenon of sending back of light rays by a surface in the same medium from which it was travelling after
striking is called Reflection. It is of two types.
Characters Regular Irregular
Reflecting Surface Smooth and polished Rough and bumpy
Image Formed Clear Blur
Example
Laws of Reflection
1) Angle of Incidence is always equal to angle of reflection.
2) Normal, incident ray and reflected ray always lie on the same plane.
3) The point where incident ray strikes the plane mirror is called point of incidence. Normal is the imaginary
line perpendicular to point of incidence.
∠1= Glance Angle of incidence
∠2= Glance Angle of reflection
SPHERICAL MIRROR
Q6) a) Define Spherical Mirror.
b) How many kinds of spherical mirrors are there?
C- 162 Govindpura Kardhani, Kalwar Road, Jhotwara, Jaipur -302012
Contact : 8890497070, 9649978593, 9782830493
