A concave lens of focal length 15 cm forms an image 10 cm from the lens. How far is the object placed from the lens? Draw the ray diagram.

By BYJU'S Exam Prep

Updated on: September 13th, 2023

It is given that

Focal length f = 15 cm

Distance of image v = – 10 cm

Let us use the formula

1/v – 1/u = 1/f

Substituting the values

1/u = – 1/10 – (-1/15)

1/u = 1/15 – 1/10

Table of content

So we get

1/u = -0.333

u = -30 cm

The object is placed 30 cm away from the concave lens

Therefore, the object is placed 30 cm away from the lens.

Summary:

A concave lens of focal length 15 cm forms an image 10 cm from the lens. The object is placed 30 cm away from the lens.

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