A concave lens has focal length 15 cm . At what distance should the object from the lens be placed so that it forms an image at 10 cm from the lens? Also find the magnification produced by the lens.

Given: The image distance, v = - 10 cm The focal length, f = - 15 cm From the lens formula, 1 f = 1 v - 1 u ⇒ 1 - 15 = 1 - 10 - 1 u ⇒ 1 u = - 1 30 ⇒ u = - 30 cm The object should be placed at 30 cm from the concave lens. The magnification, m = v u = - 10 - 30 = + 0 . 33 The magnification produced by the lens is + 0 . 33 .

E M B I B E

Science for Tenth Class Part - 1 Physics>Chapter 5 - Refraction of Light>Short Answer Type Questions>Q 9

EASY

10th CBSE

IMPORTANT

Earn 100

An object lies at a distance of $2 f$ from a concave lens of focal length $f$ . Draw a ray-diagram to illustrate the image formation.

Important Questions on Refraction of Light

EASY

10th CBSE

IMPORTANT

Science for Tenth Class Part - 1 Physics>Chapter 5 - Refraction of Light>Short Answer Type Questions>Q 10

Show by drawing a ray-diagram that the image of an object formed by a concave lens is virtual, erect and diminished.

EASY

10th CBSE

IMPORTANT

Science for Tenth Class Part - 1 Physics>Chapter 5 - Refraction of Light>Short Answer Type Questions>Q 11

Give the position, size and nature of image formed by a concave lens when the object placed:

Anywhere between optical centre and infinity.

EASY

10th CBSE

IMPORTANT

Science for Tenth Class Part - 1 Physics>Chapter 5 - Refraction of Light>Short Answer Type Questions>Q 11

Give the position, size and nature of image formed by a concave lens when the object placed:

At infinity.

EASY

10th CBSE

IMPORTANT

Science for Tenth Class Part - 1 Physics>Chapter 5 - Refraction of Light>Short Answer Type Questions>Q 12

Which type of lens is: (a) a converging lens, and which is (b) a diverging lens? Explain your answer with diagrams.

MEDIUM

10th CBSE

IMPORTANT

Science for Tenth Class Part - 1 Physics>Chapter 5 - Refraction of Light>Short Answer Type Questions>Q 13

With the help of a diagram, explain why the image of an object viewed through a concave lens appears smaller and closer than the object.

MEDIUM

10th CBSE

IMPORTANT

Science for Tenth Class Part - 1 Physics>Chapter 5 - Refraction of Light>Short Answer Type Questions>Q 14

How would a pencil look like if you saw it through (a) a concave lens and (b) a convex lens? (Assume the pencil is close to the lens). Is the image real or virtual?

EASY

10th CBSE

IMPORTANT

Science for Tenth Class Part - 1 Physics>Chapter 5 - Refraction of Light>Long Answer Type Questions>Q 15

An object is placed