A lens of focal length 15cm forms an erect image which is three times the size of the object. The distance between the object and the image is ___.
-
A.
10cm -
B.
20cm -
C.
30cm -
D.
40cm
Correct Answer: Option D
Explanation
F= 15cm
M = 3
M = (frac{v}{u})
V =3u
(frac{1}{f}) = (frac{1}{u}) + (frac{1}{v})
(frac{1}{15}) = (frac{1}{u}) – (frac{1}{3u})
(frac{1}{15}) = (frac{2}{3u})
U =10cm
D = u + v
= 10 +30 = 40cm
There is an explanation video available below.