A lens of focal length 15.0 cm forms an upright image four times the size of an object. Calculate the distance of the image from the lens
a
11.3cm
b
18.8 cm
c
37.5cm
d
45.0cm
e
75.0cm
Explanation
Correct Option
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Discussions (11)

Faroukalao
4 years ago
D... 45cm
Virtual, Upright and magnified shows a convex(converging) lens where the object if between F and the Pole
In this case V is negative
f = uv/u+v
M = v/u
4 = v/u
v = 4u
15 = -4u × u/(-4u + u)
15 = -4u²/-3u
15 = 4u/3
45 = 4u
u = 11.25cm
v = 4u
v = 45
... v = 45cm

Nnaaaaa
7 years ago
Upright image ia virtual and its negative
If its real
M=V/F -1
If it is virtual
M=V/F + 1
SO HERE ITS VIRTUAL WE USE THE SECOND FORMULA
M=4 f=15
4-1=v/15
V=15×3=45cm√√√

raph.Montella
9 years ago
Here is an explanation:
M=4, f=15cm, v= ?
M=(v/f) -1
4=(v/15) -1
4+1= v/15
5=v/15
15*5 =v
75=v
75.0cm = v
REF: Check: Essential Physics, page 227




