with¤क...Let’s consider convex mirror Where will the reflected ray go? C r i This is the...
Transcript of with¤क...Let’s consider convex mirror Where will the reflected ray go? C r i This is the...
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Focus of Concave & Convex Mirrors
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Ray Diagrams of Convex Mirrors
Focus
Sign Convention of Mirrors & Mirror Formula
Refraction and Refractive Index
Standard Incident Rays
Ray Diagrams of Concave Mirrors
Ray Diagrams of Concave & Convex Lenses
Sign Convention of Lenses & Lens Formula
Numericals on Mirrors, Lenses & Refractive Index
Ray Diagrams of Convex Mirrors
Focus
Sign Convention of Mirrors & Mirror Formula
Refraction and Refractive Index
Standard Incident Rays
Ray Diagrams of Concave Mirrors
Ray Diagrams of Concave & Convex Lenses
Sign Convention of Lenses & Lens Formula
Numericals on Mirrors, Lenses & Refractive Index
Convex Mirror Concave Mirror
A B
Q1. A mirror with its reflecting surface curved inwards is called
Plane mirror
C
None of the above
D
Convex Mirror Concave Mirror
A B
Q1. A mirror with its reflecting surface curved inwards is called
Plane mirror
C
None of the above
D
Convex mirror Concave mirror
Plane mirror
None of the above
A B
C D
Q2. If size of the image is not same as size of the object then, it is not a
Convex mirror Concave mirror
Plane mirror
None of the above
A B
C D
Q2. If size of the image is not same as size of the object then, it is not a
PoleCentre of curvature
Principal axis
Aperture
A B
C D
Q3. The entire reflecting area of mirror is called?
PoleCentre of curvature
Principal axis
Aperture
A B
C D
Q3. The entire reflecting area of mirror is called?
ANSWER : Pole
Q6. Midpoint of the aperture of a mirror is called ……..
FOCUS
Let’s consider an incident ray in a concave mirror?
Incident ray
Concave mirror
C
Where would the reflected ray go?
1
2
3
?
??
C
Now let’s apply law of reflection to concave mirror
Incident ray
Concave mirror
C
What is angle of incidence?
Reflected ray & Normal
Incident ray & normal
A B
Angle of incidence is the angle between?
None of theseIncident ray and reflected ray
C D
Reflected ray & Normal
Incident ray & normal
A B
Angle of incidence is the angle between?
None of theseIncident ray and reflected ray
C D
Where is the normal in a concave mirror?
Incident ray
C
Normal of a plane mirror
Plane mirror
Normal
Concave mirror
Let’s draw a normal on a circle.
O
P
Normal is perpendicular to the tangent
P
ONorm
al
Normal passes through the centre
So, we can easily find the direction of the reflected ray
C
B
So, we can easily find the direction of the reflected ray
C
B
BC is the normal
So, we can easily find the direction of the reflected ray
C
Bi
BC is the normal
Measure i
So, we can easily find the direction of the reflected ray
BC is the normal
Measure iDraw r at point B such that i = r
Let’s consider another ray
Let’s consider another ray
The ray passes through the same point on the principal axis
All rays pass through the same point on the principal axis after reflection.
All rays pass through the same point on the principal axis after reflection.
The point is called FOCUS and is denoted by F
F
All the rays converge at one point .
Focus is a point at which rays of light meets after Reflection
Concave mirror → Converging mirror
F
Let’s consider convex mirror
C
Let’s consider convex mirror
Where will the reflected ray go?
C
Let’s consider convex mirror
Where will the reflected ray go?
C
ri
This is the reflected ray
After reflection, they seem to spread out.- (DIVERGE)
Convex mirror → Diverging mirror
C
To an observer it appears that rays are originating from a point behind the mirror.
CF
That is FOCUS in case of a convex mirror
In Concave Mirror Focus is in front of the mirror.
In Convex Mirror Focus is behind the the mirror.
In Concave Mirror Focus is in front of the mirror.
In Convex Mirror Focus is behind the the mirror.
Real Focus
Virtual Focus
Relation between R and F
We Know focus lies on the principal axis.
Concave mirror
CP
F C
Convex mirror
FP
What is the distance between pole and centre of curvature
What is the distance between pole and centre of curvature
Similarly , distance between pole and focus is called Focal length. Denoted by ‘f ‘
Concave mirror
CP
F C
Convex mirror
FP
f f
Focal length is half the radius of curvature
Concave mirror
CP
F C
Convex mirror
FP
f fR R
Focal length is half the radius of curvature
Concave mirror
CP
F C
Convex mirror
FP
f fR R
F= R2
R = 2 F
V I P
Q1. To draw a normal at point S, we should join point S to
P Q
O S
A B
C D
Q1. To draw a normal at point S, we should join point S to
P Q
O S
A B
C D
Q1. To draw a normal at point S, we should join point S to
All the parallel rays meet at the same point after reflection
All the parallel rays converge after reflection
A ray parallel to the principal axis pass through the center of curvature after reflection
All the rays parallel to the principal axis meet at the focus
A
B
C
D
Q2. Which of the statements is not true about a concave mirror?
All the parallel rays meet at the same point after reflection
All the parallel rays converge after reflection
A ray parallel to the principal axis pass through the center of curvature after reflection
All the rays parallel to the principal axis meet at the focus
A
B
C
D
Q2. Which of the statements is not true about a concave mirror?
15 cm 20 cm
10 cm 5 cm
A B
C D
Q3. If focus is located 10 cm from the pole , What is the value of R ?
15 cm 20 cm
10 cm 5 cm
A B
C D
Q3. If focus is located 10 cm from the pole , What is the value of R ?
15 cm 10 cm
30 cm 60 cm
A B
C D
Q4. If the radius of curvature of a convex mirror is 30 cm, What will be the focal length? [Boards 2011]
15 cm 10 cm
30 cm 60 cm
A B
C D
Q4. If the radius of curvature of a convex mirror is 30 cm, What will be the focal length? [Boards 2011]
100 cm Convex mirror
25 cm Convex mirror
25 cm Concave mirror
100 cm Concave mirror
A B
C D
Q5. The outer surface of a hollow sphere of aluminium of radius 50 cm is to be used as a mirror. What will be the focal length of this mirror? Which type of spherical mirror will it provide?
[Boards 2010]
100 cm Convex mirror
25 cm Convex mirror
25 cm Concave mirror
100 cm Concave mirror
A B
C D
Q5. The outer surface of a hollow sphere of aluminium of radius 50 cm is to be used as a mirror. What will be the focal length of this mirror? Which type of spherical mirror will it provide?
[Boards 2010]
Q6. The point where rays parallel to principal axis meet after reflection is
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