Refractive index of water is 4 3 and glass is 3 2 with respect to air. What is the refractive index of glass with respect to water?

Refractive index of glass with respect to water is the ratio of refractive index of glass to the refractive index of water. Given, Refractive index of water = 4 3 . Refractive index of glass = 3 2 . R e f r a c t i v e i n d e x o f g l a s s w . r . t w a t e r = R e f r a c t i v e i n d e x o f g l a s s R e f r a c t i v e i n d e x o f w a t e r = 3 2 4 3 = 1.125

Size of the 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, magnification, m = 1 3 focal length, f = 20 cm We know that magnification in terms of distance is given as: m a g n i f i c a t i o n = - i m a g e d i s t a n c e o b j e c t d i s t a n c e m = - v u v = - 1 3 u We also know that for a spherical mirror, 1 v + 1 u = 1 f Substituting the values, We get, - 3 u + 1 u = 1 f - 2 u = 1 f u = - 2 f = - 40 cm v = - 1 3 ( - 40 ) = 13 . 34 cm Thus, the image is formed between the focus and pole on the convex mirror and it is virtual and erect. Hence, the mirror is convex.

A student focused 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 on the screen as Position of the candle = 12 cm Position of the convex lens = 50 cm Position of the screen = 88 cm What is the focal length of the convex lens? Where will the image be formed if he shifts the candle towards the lens at a position of 31 cm What will be the nature of the image formed if he further shifts the candle towards the lens? Draw a ray diagram to show the formation of image in case of (c) as said above.

Given, Position of the candle = 12 cm Position of the convex lens = 50 cm Position of the screen = 88 cm Now, the position of the candle from the convex lens, u = 50 - 12 = 38 cm The position of the screen, v = 88 - 50 = 38 cm a. The lens formula is 1 v - 1 u = 1 f 1 38 + 1 38 = 1 f 2 38 = 1 f f = 19 cm b. The position of the object now changed to 31 cm Now the distance of the object is, u = 50 - 31 = 19 cm 1 v - 1 u = 1 f 1 v + 1 19 = 1 f v = 1 0 = i n f i n i t y The image is formed at infinity. c. If he further shifts the candle towards the optic centre, the image formed will be virtual, erect and magnified. It is on the same side of the object. d. Ray diagram to show the formation of the virtual image as mentioned:

E M B I B E

Concise Physics A Textbook of Science for Class X>Chapter 1 - Part -1>Light: Reflection and Refraction>Q 6

MEDIUM

10th CBSE

IMPORTANT

Earn 100

What are the sign conventions rules for spherical lenses?

Important Questions on Light: Reflection and Refraction

MEDIUM

10th CBSE

IMPORTANT

Concise Physics A Textbook of Science for Class X>Chapter 1 - Part -1>Light: Reflection and Refraction>Q 7

What are the uses of concave and convex mirrors?

MEDIUM

10th CBSE

IMPORTANT

Concise Physics A Textbook of Science for Class X>Chapter 1 - Part -1>Light: Reflection and Refraction>Q 8

Distinguish between real and virtual image in a lens?

MEDIUM

10th CBSE

IMPORTANT

Concise Physics A Textbook of Science for Class X>Chapter 1 - Part -1>Light: Reflection and Refraction>Q 9

What is the nature of image of an object when it moved from infinity to the convex lens?

EASY

10th CBSE

IMPORTANT

Concise Physics A Textbook of Science for Class X>Chapter 1 - Part -1>Light: Reflection and Refraction>Q 10

What is magnification of lens?

MEDIUM

10th CBSE

IMPORTANT

Concise Physics A Textbook of Science for Class X>Chapter 1 - Part -1>Light: Reflection and Refraction>Q 11

Refractive index of water is

\frac{4}{3}

and glass is

\frac{3}{2}

with respect to air. What is the refractive index of glass with respect to water?

MEDIUM

10th CBSE

IMPORTANT

Concise Physics A Textbook of Science for Class X>Chapter 1 - Part -1>Light: Reflection and Refraction>Q 12

Size of the 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

Concise Physics A Textbook of Science for Class X>Chapter 1 - Part -1>Light: Reflection and Refraction>Q 13

A student focused 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 on the screen as
Position of the candle =

12 cm

Position of the convex lens =

50 cm

Position of the screen =

88 cm

What is the focal length of the convex lens?
Where will the image be formed if he shifts the candle towards the lens at a position of $31 cm$
What will be the nature of the image formed if he further shifts the candle towards the lens?
Draw a ray diagram to show the formation of image in case of (c) as said above.

MEDIUM

10th CBSE

IMPORTANT

Concise Physics A Textbook of Science for Class X>Chapter 1 - Part -1>Light: Reflection and Refraction>Q 14

Draw a ray diagram showing the image formation by a concave mirror when an object is placed between the pole and focus of the mirror.