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>Questions Based on High Order Thinking Skills (HOTS)>Q 18

EASY

10th CBSE

IMPORTANT

Earn 100

A camera fitted with a lens of focal length $50 mm$ is being used to photograph a flower that is $5 cm$ in a diameter. The flower is placed $20 cm$ in front of the camera lens.

What would be the diameter of the image of the flower on the film?

Important Questions on Refraction of Light

EASY

10th CBSE

IMPORTANT

Science for Tenth Class Part - 1 Physics>Chapter 5 - Refraction of Light>Questions Based on High Order Thinking Skills (HOTS)>Q 18

A camera fitted with a lens of focal length $50 mm$ is being used to photograph a flower that is $5 cm$ in a diameter. The flower is placed $20 cm$ in front of the camera lens.

What is the nature of the camera lens?

EASY

10th CBSE

IMPORTANT

Science for Tenth Class Part - 1 Physics>Chapter 5 - Refraction of Light>Questions Based on High Order Thinking Skills (HOTS)>Q 19

An object is

2 m

from a lens which forms an erect image one-fourth (exactly) the size of the object. Determine the focal length of the lens. What type of lens is this?

EASY

10th CBSE

IMPORTANT

Science for Tenth Class Part - 1 Physics>Chapter 5 - Refraction of Light>Questions Based on High Order Thinking Skills (HOTS)>Q 20

An image formed on a screen is three times the size of the object. The object and screen are $80 cm$ apart when the image is sharply focused.

(a) State which type of lens is used.

(b) Calculate focal length of the lens.

EASY

10th CBSE

IMPORTANT

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

The lens

A

has a focal length of

25 cm

whereas another lens

B

has a focal length of

60 cm

. Giving reason state, which lens has more power:

A

or

B

.

EASY

10th CBSE

IMPORTANT

Science for Tenth Class Part - 1 Physics>Chapter 5 - Refraction of Light>Very Short Answer Type Questions>Q 2

Which causes more bending (or more refraction) of light rays passing through it: a convex lens of long focal length or a convex lens of short focal length?

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10th CBSE

IMPORTANT

Science for Tenth Class Part - 1 Physics>Chapter 5 - Refraction of Light>Very Short Answer Type Questions>Q 3

Name the physical quantity whose unit is dioptre.

EASY

10th CBSE

IMPORTANT

Science for Tenth Class Part - 1 Physics>Chapter 5 - Refraction of Light>Very Short Answer Type Questions>Q 4

Define