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

Concave lens

Converging lens

Diverging lens

Light rays are converged

Light rays are diverged

P.66

Light ray bendstowards normalwhen it travelsfrom less densemedium todenser medium

Light ray bendsaway from normalwhen it travelsfrom denser mediumto less dense medium

P.66

Light ray bendstowards normalwhen it travelsfrom less densemedium todenser medium

Light ray bendsaway fromnormal when ittravels fromdenser mediumto less densemedium

P.66

CF F’2F 2F’

f

P.66

CF F’2F 2F’

f

P.66

Compare f and f’

P.66

P.66

P.67

Locate the image ofa distant object

f = separation between the lens & screen

P.67

fP.67

Image is inverted

Same size

u = v

P.67

fP.67

P.68

F

F’

P.68

P.68

P.68

Focal length f

Thin lens

Thick lens

Refractive index n

Radii of curvature

Long focal length

Short focal length

P.68

C

Light ray passes straightthrough the optical centre

P.68 Rule 1

C

Light ray passes straightthrough the optical centre

P.68 Rule 1

F

P.68 Rule 2

F

P.68 Rule 2

F

P.68 Rule 3

F’F

P.68 Rule 3

P.69

Concave Lens

Diverging

X

X

X

X

P.69

Rule 2Correct

Diverging

Rule 3Correct

Rule 3 Correct

Correct

ConvergingIncorrect

Experiment : Construction rulesP.69

Object O

F F’

Any 2 light rays from construction rules

Image I

Solid lines denote real light ray & real image

P.69

Object O

F F’

Any 2 light rays from construction rules

Dotted lines denote line extended & virtual image

Image I

P.69

P.69

Object O

F F’

Image I

P.69 Q1

P.69

F F’

O

I

P.69

Can find the location of the image

F F’

O

I

P.69

Can find the location of the object

O

I

P.69

Can find the location of lens

Ray diagram

Object Image Focal length

Any 2 3rd

P.69

P.70

F F’

I

u = Object at infinity is representedby a set of parallel light rays

ImageReal

Inverted

Diminished v = f

P.70

P.70

P.70

I

u > 2f

O

F F’2F 2F’

Image2f > v > f

Real

Inverted

Diminished

P.70

P.70

P.70

I

u = 2f

Same size

O

F F’2F

2F’

v = 2fImage

Real

Inverted

P.70

P.70

I

2f > u > f

Enlarged

O

F F’2F 2F’

v > 2fImage

Real

Inverted

P.70

P.70

F F’

u = f

v =

O

ImageReal

Inverted

Image at infinityis representedby a set of parallellight rays

P.70

P.70

Iu < f

Virtual Upright

O

F F’2F 2F’

Same sideEnlargedImage

P.70

P.70

P.70

Object

Image

Infinity

F

Real

Inverted

Diminished

Same size

Enlarged

2F F

2F Infinity

P.70

F

Object

Image Virtual Erect Same side

Enlarged

Optical centre

Infinity Optical centre

Same size

P.70

F F’

I

ImageReal

Inverted

Diminished v = f

P.71 Q1

I

Enlarged

O

F F’2F 2F’

v > 2fImage

Real

Inverted

P.71 Q1

P.71

Diverging

Bends towards normal

F F’

I

O

Same side& betweenC & F

Virtual UprightImage

Diminished

P.72

P.72

P.72

F

Object

Image

Optical centreInfinity

Optical centre

Virtual Erect Same side

Diminished Same size

P.72

P.72 Q1

Diverging

Light can pass through it

Must be Lens

P.72 Q2

Concave Lens

Virtual Image

X X

Only 2 rays from tip

X

P.73 Q3

Erect

Diminished(1 mark)

Concave Lens(1 mark)

F F’

I

O

Same side& betweenC & F

Virtual UprightImage

Diminished

P.73 Q3

Experiment : Image formation using light raysP.73

Ray diagram

Position of image

Size of image

Nature of image

P.73

I

O

F F’2F 2F’

P.73

I

O

F F’2F 2F’

P.73

F F’

O

I

Scale

P.73

P.74 Q1

P.74 Q1

I

Same size v = 2fImage

Real

Inverted

f= 15 cm

I

hi

O

ho

u

v

h

hmo

iu

v

P.74 Magnification

I

O

F F’2F

2F’

P.74

F F’

I

O

P.74

u

v

u = v

2f

fvu

111

f>0, convex lens

f<0, concave lens

v>0, real image

v<0, virtual image

P.75 Q1

Real Image

(1) is correct

(2) is correct

(3) is incorrect

Only inverted

Real &invertedimage

RR

P.75 Q1

P.75 Q2

Convex lens Real image, on the other side

J

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)

I

Image is outside the shaded region

P.77 Q3

P.77 Q3(c)(ii)

I

f=5.5 cm

I

P.78 Q2

Real Image Virtual Image

Virtual Image

P.78 Q3

Can you see Virtual Image?

Yes

Camera acts as your eyes

False

This is real image

Image should be formed on film

True

P.79 Q4

Real Image

Enlarged, erect & virtual image

Magnifying glass is convex lens

P.79

P.79

I

O

F F’2F 2F’

The magnification ismaximum when the objectis close to the focus

P.79

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

X Convex lensVirtual, under the lensX

u < f to have magnified virtual imageX

D) v>u to have magnified virtual image

X

I

O

F F’2F 2F’

P.80 Q5

True False

P.80 Q6

F F’I

XYesYes

P.80 Q8

XMagnified image by convex lens

YesYes

P.80 Q11

Yes Magnifying glass

YesYes