Transcript P.66 Convex lens Thicker central part P.66 Concave lens Thinner central part P.66 Cylindrical convex lens Convex in 1 direction only P.66 Cylindrical concave lens Concave in 1 direction only P.66 Convex lens Converging.

P.66
Convex lens
Thicker central part
P.66
Concave lens
Thinner central part
P.66
Cylindrical convex lens
Convex in 1 direction only
P.66
Cylindrical concave lens
Concave in 1 direction only
P.66
Convex lens
Converging lens
Light rays are converged
Concave lens
Diverging lens
Light rays are diverged
P.66
Light ray bends
towards normal
when it travels
from less dense
medium to
denser medium
Light ray bends
away from normal
when it travels
from denser medium
to less dense medium
P.66
Light ray bends
towards normal
when it travels
from less dense
medium to
denser medium
Light ray bends
away from
normal when it
travels from
denser medium
to less dense
medium
P.66
f
2F
F
C
F’
2F’
P.66
f
2F
F
C
F’
2F’
P.66
Compare f and f’
P.66
P.67
P.67
Locate the image of
a distant object
f = separation between
the lens & screen
P.67
f
u=v
Same size
Image is inverted
P.67
P.67
f
P.68
P.68
F
F’
P.68
P.68
P.68
Refractive index n
Focal length f
Radii of curvature
Thin lens
Long focal length
Thick lens
Short focal length
P.68
Rule 1
C
Light ray passes straight
through the optical centre
P.68
Rule 1
C
Light ray passes straight
through the optical centre
P.68
Rule 2
F
P.68
Rule 2
F
P.68
Rule 3
F
P.68
Rule 3
F
F’
P.69
X
Concave Lens
Diverging
X
X
X
P.69
Rule 2
Correct
Diverging
Correct
Rule 3
Rule 3
Correct
Correct
Converging
Incorrect
P.69
Experiment : Construction rules
Solid lines denote real light ray & real image
Object O
F
P.69
F’
Image I
Any 2 light rays from construction rules
Dotted lines denote line extended & virtual image
Object O
F Image I
F’
P.69
Any 2 light rays from construction rules
P.69
P.69 Q1
Object O
F
F’
Image I
P.69
P.69
O
F
F’
I
Can find the location of the image
P.69
O
F
F’
I
Can find the location of the object
P.69
O
I
Can find the location of lens
P.69
Ray diagram
Object
Any 2
Image
Focal length
3rd
P.70
P.70
F
F’
I
Real
Image
Inverted
u=
Object at infinity is represented
by a set of parallel light rays
Diminished
v=f
P.70
P.70
P.70
u > 2f
O
F
F’
2F’
I
Real
Inverted
2F
Image
Diminished
2f > v > f
P.70
P.70
P.70
u = 2f
O
F
F’
Real
2F’
I
Inverted
2
F
Image
Same size v = 2f
P.70
P.70
2f > u > f
O
F’
F
Real
2F’
Inverted
2F
Image
Enlarged
I
v > 2f
P.70
u=f
O
Image at infinity
is represented
by a set of parallel
light rays
F’
F
Real
Image
v = 
Inverted
P.70
P.70
P.70
u<f
I
O
2F
F
F’
2F’
Virtual Upright
Image
Enlarged
Same side
P.70
P.70
P.70
Object
Image
2F
F
Inverted
Infinity
Real
Same size
F
2F
Diminished
Infinity
Enlarged
P.70
Object
F
Optical centre
Image
Virtual
Infinity
Enlarged
Erect
Same side
Optical centre
Same size
P.71 Q1
F
F’
I
Image
Inverted
Real
Diminished
v=f
P.71 Q1
O
F’
F
Real
2F’
Inverted
2F
Image
Enlarged
I
v > 2f
P.71
Diverging
Bends towards normal
P.72
O
I
F
F’
Virtual Upright
Image
Diminished
Same side
& between
C&F
P.72
P.72
P.72
Object
Infinity
Image
Optical centre
Virtual
F
Erect
Same side
Optical centre
Diminished
Same size
P.72 Q1
Diverging
Light can pass through it
Must be Lens
P.72 Q2
Concave Lens
Virtual Image
Only 2 rays from tip
X
X
X
P.73 Q3
Erect
Diminished
(1 mark)
Concave Lens
(1 mark)
P.73 Q3
O
I
F
F’
Virtual Upright
Image
Diminished
Same side
& between
C&F
P.73
Experiment : Image formation using light rays
P.73
Position of image
Ray diagram
Size of image
Nature of image
P.73
O
2F
F
F’
2F’
I
P.73
O
2F
F
F’
2F’
I
P.73
Scale
O
F
F’
I
P.74 Q1
P.74 Q1
f= 15 cm
I
Inverted
Real
Image
Same size v = 2f
P.74
Magnification
O
v
h
i

m
ho u
v
ho
u
hi
I
P.74
I
O
2
F
F
F’
2F’
P.74
O
I
F
F’
v
1 1 1
 
u v f
f>0, convex lens
u=v
f<0, concave lens
v>0, real image
v<0, virtual image
2f
u
P.75 Q1
Real Image
(1) is correct
(2) is correct
(3) is incorrect
Only inverted
P.75 Q1
R
Real &
inverted
image
R
P.75 Q2
Real image, on the other side
J
Convex lens
P.75 Q2
36 cm
m=v/u
= 36/18
=2
P.75 Q2
24 cm
u=v=2 f
f = 12 cm
P.76 Q2
P.76 Q2
Magnifying glass
It cannot. The image is virtual.
P.76 Q3
P.76 Q3
I
u =30 cm
v =7.5 cm
m =v / u = 7.5 / 30 = 0.25
P.76 Q3
Convex lens will form inverted, real image when the object is placed beyond
the focal length of the lens. The visitor cannot be easily identified.
P.77 Q3
P.77 Q3
P.77 Q3(c)(i)
Image is outside
the shaded region
I
P.77 Q3
P.77 Q3(c)(ii)
f=5.5 cm
II
P.78 Q2
Real Image
Virtual Image
Virtual Image
P.78 Q3
Can you see Virtual Image?
Yes
Image should be formed
on film
Camera acts as your eyes
This is real image
False
True
P.79 Q4
Real Image
P.79
Enlarged, erect & virtual image
Magnifying glass is convex lens
P.79
P.79
The magnification is
maximum when the object
is close to the focus
I
O
2F
F
F’
2F’
P.79 Q2
Converge light ray
Convex lens
Convex lens
Concave mirror
(out of syllabus)
Convex lens
P.79 Q3
out of syllabus
P.80 Q4
I
2
F
X
X
X
X
O
F’
F
2F’
Convex lens
Virtual, under the lens
u < f to have magnified virtual image
D) v>u to have magnified virtual image
P.80 Q5
True
False
P.80 Q6
X
Yes
Yes
F
F’
I
P.80 Q8
X
Yes
Yes
Magnified image by convex lens
P.80 Q11
Yes
Yes
Yes
Magnifying glass