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>Long Answer Type Questions>Q 32

EASY

10th CBSE

IMPORTANT

Earn 100

An object is placed well outside the principal focus of a convex lens. Draw a ray diagram to show how the image formed, and say whether the image is real or virtual.

Important Questions on Refraction of Light

HARD

10th CBSE

IMPORTANT

Science for Tenth Class Part - 1 Physics>Chapter 5 - Refraction of Light>Long Answer Type Questions>Q 32

What is the effect on the size and position of the image of moving the object towards the lens.

HARD

10th CBSE

IMPORTANT

Science for Tenth Class Part - 1 Physics>Chapter 5 - Refraction of Light>Long Answer Type Questions>Q 32

What is the effect on the size and position of the image on moving the object away from the lens?

EASY

10th CBSE

IMPORTANT

Science for Tenth Class Part - 1 Physics>Chapter 5 - Refraction of Light>Long Answer Type Questions>Q 33

Explain what is meant by a virtual, magnified image.

EASY

10th CBSE

IMPORTANT

Science for Tenth Class Part - 1 Physics>Chapter 5 - Refraction of Light>Long Answer Type Questions>Q 33

Draw a ray diagram to show the formation of a virtual magnified image of an object by a convex lens. In your diagram, the position of object and image with respect to the principal focus should be shown clearly.

HARD

10th CBSE

IMPORTANT

Science for Tenth Class Part - 1 Physics>Chapter 5 - Refraction of Light>Long Answer Type Questions>Q 33

Three convex lenses are available having focal lengths of

4 cm, 40 cm

and

4 m

respectively. Which one would you choose as a magnifying glass and why?

MEDIUM

10th CBSE

IMPORTANT

Science for Tenth Class Part - 1 Physics>Chapter 5 - Refraction of Light>Long Answer Type Questions>Q 34

Explain why, a real image can be projected on a screen but a virtual image cannot.

EASY

10th CBSE

IMPORTANT

Science for Tenth Class Part - 1 Physics>Chapter 5 - Refraction of Light>Long Answer Type Questions>Q 34

Draw a ray diagram to show the formation of a real diminished image of an object by a convex lens. In your diagram, the position of object and image with respect to the principal focus should be shown clearly.

EASY

10th CBSE

IMPORTANT

Science for Tenth Class Part - 1 Physics>Chapter 5 - Refraction of Light>Multiple Choice Questions (MCQs)>Q 35

A convex lens has a focal length of