Question

An object of height 2 cm is placed in front of a convex lens of focal length 20 cm at a distance of 15 cm from it. Find the position and magnification of the image.

Answer 1

Answer:

v = 60 cm

m = 4

Explanation:

Given :-

O = 2 cm (positive)

f = 20 cm (positive)

u = 15 cm (negative)

To find :-

Position and magnification of the image.

Solution :-

Using lens formula:

• 1/v - 1/u = 1/f
• 1/v - (1/-15) = 1/20
• 1/v = 1/20 - 1/15
• v = -1/60
• v = 60 cm (negative)

Magnification:

• m = v/u
• -60/-15
• 4 (positive)

∴ Image is erect in size (8 cm) four times the object and virtual, enlarged.

Answer 2

Answer:

$v = 60 \: cm$

$m = 4$

Explanation:

It is the correct answer.

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