Page 264 - text book form physics kssm 2020

Activity 6.10 shows that image size formed by a lens depends on the position of the object
from the centre of the lens. Comparison between image size and object size is made based on the
ratio of image height to object height. Th is ratio is known as linear magnifi cation, m.

image height, h i
Linear magnifi cation, m =
object height, h o

h o
2F F F 2F Image
Object

h
i

u v

Figure 6.34 Formation of image by convex lens

Based on Figure 6.34, ratio of image height to object height
is also the same as the ratio of image distance to object distance.
File

image distance, v
Linear magnifi cation, m = Linear magnifi cation, m does
object distance, u
not have a unit.
As such, linear magnifi cation can be formulated as,
h i v m 1 Image diminished
m = = , where h = image height
i
h o u h = object height m = 1 Image same size
o
v = image distance as object
u = object distance m 1 Image magnifi ed

Formative Practice 6.3
6.3
Figure 6.35 shows an image seen through a convex lens with focal
length of 10 cm.
12
13
1. What are the characteristics of the image? 15
7
19
2. Draw a ray diagram to show how the image in the fi gure
is formed. 21
18 23

3. Suggest a suitable position to place the object to produce an
inverted image. Figure 6.35

258 6.3.4
258
6.3.4