Size of image of an object by a mirror having a focal length of 20 cm is observed to be reduced to 1 3 rd of its size. At what distance the object has been placed from the mirror? What is the nature of the image and the mirror?

Given that, Focal length, f = 20 cm Magnification, m = 1 3 Case-I: When the mirror is concave, f = - 20 cm m = - v u where, v is the image distance and u is the object distance. That is, - v u = - 1 3 or v = u 3 Using mirror formula 1 f = 1 v + 1 u we can write, 1 - 20 = 1 u 3 + 1 u or u = - 80 cm As the image is formed on the same side as that of the object, it will be real and inverted. Case-II: When the mirror is convex, f = + 20 cm m = - v u = 1 3 or v = - u 3 Using mirror formula 1 f = 1 v + 1 u we can write, 1 20 = 1 - u 3 + 1 u or u = - 40 cm As the image is formed behind the mirror, it will be virtual and erect.

MEDIUM

10th CBSE

IMPORTANT

Earn 100

Draw ray diagrams showing the image formation by a concave lens when an object is placed between focus and twice the focal length of the lens.

Important Questions on Light - Reflection and Refraction

MEDIUM

10th CBSE

IMPORTANT

Science Part-I NEW ERA PHYSICS Textbook for Class X>Chapter 4 - Light - Reflection and Refraction>NCERT EXEMPLAR PROBLEMS>Q 33

Draw ray diagrams showing the image formation by a concave lens when an object is placed beyond twice the focal length of the lens.

MEDIUM

10th CBSE

IMPORTANT

Science Part-I NEW ERA PHYSICS Textbook for Class X>Chapter 4 - Light - Reflection and Refraction>NCERT EXEMPLAR PROBLEMS>Q 34

Draw ray diagrams showing the image formation by a convex mirror when an object is placed at infinity.

MEDIUM

10th CBSE

IMPORTANT

Science Part-I NEW ERA PHYSICS Textbook for Class X>Chapter 4 - Light - Reflection and Refraction>NCERT EXEMPLAR PROBLEMS>Q 34

Draw ray diagrams showing the image formation by a convex mirror when an object is placed at finite distance from the mirror.

MEDIUM

10th CBSE

IMPORTANT

Science Part-I NEW ERA PHYSICS Textbook for Class X>Chapter 4 - Light - Reflection and Refraction>NCERT EXEMPLAR PROBLEMS>Q 35

The image of a candle flame formed by a lens is obtained on a screen placed on the other side of the lens. If the image is three times the size of the flame and the distance between lens and image is

80 cm

, at what distance should the candle be placed from the lens? What is the nature of the image at a distance of

80 cm

from the lens?

MEDIUM

10th CBSE

IMPORTANT

Science Part-I NEW ERA PHYSICS Textbook for Class X>Chapter 4 - Light - Reflection and Refraction>NCERT EXEMPLAR PROBLEMS>Q 36

Size of image of an object by a mirror having a focal length of

20 cm

is observed to be reduced to

\frac{1}{3}

rd of its size. At what distance the object has been placed from the mirror? What is the nature of the image and the mirror?

MEDIUM

10th CBSE

IMPORTANT

Science Part-I NEW ERA PHYSICS Textbook for Class X>Chapter 4 - Light - Reflection and Refraction>NCERT EXEMPLAR PROBLEMS>Q 37

Define power of a lens. What is its unit? One student uses a lens of focal length

50 cm

and another of

- 50 cm

. What is the nature of the lens and its power used by each of them?

MEDIUM

10th CBSE

IMPORTANT

Science Part-I NEW ERA PHYSICS Textbook for Class X>Chapter 4 - Light - Reflection and Refraction>NCERT EXEMPLAR PROBLEMS>Q 38

A student focussed the image of a candle flame on a white screen using a convex lens. He noted down the position of the candle screen and the lens as under

Position of Candle $= 12.0 cm$

Position of convex lens $= 50.0 cm$

Position of the screen $= 88.0 cm$

What is the focal length of the convex lens?

MEDIUM

10th CBSE

IMPORTANT

Science Part-I NEW ERA PHYSICS Textbook for Class X>Chapter 4 - Light - Reflection and Refraction>NCERT EXEMPLAR PROBLEMS>Q 38

A student focussed the image of a candle flame on a white screen using a convex lens. He noted down the position of the candle screen and the lens as under

Position of Candle $= 12.0 cm$

Position of convex lens $= 50.0 cm$

Position of the screen $= 88.0 cm$

Where will the image be formed if he shifts the candle towards the lens at a position of $31.0 cm$ ?

Draw ray diagrams showing the image formation by a concave lens when an object is placed between focus and twice the focal length of the lens.

Important Questions on Light - Reflection and Refraction

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