Class 10- Physics Light - Reflection and RefractionContact Number: 9667591930 / 8527521718

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The number of images formed by two plane mirrors inclined at an angle ${60}^{\xb0}$ of an object placed symemetrically between mirrors is

1. 5

2. infinite

3. 6

4. 7

Choose the wrong statement.

1. A concave mirror can form a magnified real image.

2. A concave mirror can form a magnified virtual image

3. A convex mirror can form a diminished virtual image.

4. A convex mirror can form a diminished real image.

Given a point source of light, which of the following can produce a parallel beam of light?

1. Concave lens

2. Two plane morrors inclined at ${90}^{\xb0}$ to each other

3. Convex mirror

4. Conacve mirror

For a real object, a convex mirror always forms an image which is

1. virtual and erect

2. real and magnified

3. real and inverted

4. virtual and inverted

An object 20 cm from a spherical mirror give rise to a virtual image 15 cm behind the mirror. The type of the mirror and its focal length is

1. concave, 8.5 cm

2. convex, 30 cm

3. concave, 60 cm

4. convex, 60 cm

An object 4 cm high is placed at a distance of 15 cm in front of a cThenonvex mirror having a radium of curvature of 10 cm. tha image formed is at a distance of

1. 7.5 cm behind the mirror

2. 3.75 cm in front of the mirror

3. 7.5 cm in front of camera

4. 3.75 cm behind the mirror

A covex mirror has a focal length 15 cm. A real object placed at a distance 15 cm in front of it from the pole, produces an image at

1. 7.5 cm

2. 30 cm

3. infinity

4. 15 cm

A person standing in front of a mirror finds his image thinner but with normal height. This inplies that the mirror is

1. convex and cylindrical with axis vertical

2. convex and cylindrical with axis horizontal

3. convex and spherical

4. cancave and spherical

A person standing in front of a mirror finds his image larger than himself. This implies that the mirror is

1. concave

2. cylindrical with bulging side outwards

3. plane

4. convex

An object is at a distance of 10 cm from a mirror and the image of the object is at a distance of 30 cm from the mirror on the same side as the object. Then the nature of the mirror and its focal length is

1. convex, 15 cm

2. concave, 1.5 cm

3. convex, 7.5 cm

4. concave, 7.5 cm

A real image of half the size is obtained in a concave spherical mirror with a radius of curvature of 40 cm. The distance of the object and that of its image will be

1. 15 cm, 30 cm

2. 30 cm, 15 cm

3. 30 cm, 60 cm

4. 60 cm, 30 cm

All of the following statements are correct except

1. a virtual, erect, magnified image can be formed using a concave mirror

2. a real, inverted, same sized image can be formed using a convex mirror

3. the magnification produced by a convex mirror is always less than one

4. a virtual, erect, same size image can be obtained by using a plane mirror

Which of the following can produce a virtual image?

1. Plane mirror

2. Concave mirror

3. Convex lens

4. All of these

An object is placed at the centre of the curvature of a concave mirror. The distance between its image and the pole is

1. equal to f

2. between f and 2f

3. equal to 2f

4. greater than 2f

An object is placed at the centre of the curvature of a concave mirror. The distance between its image and the pole is

1. equal to f

2. between f and 2f

3. equal to 2f

4. greater than 2f

If an incident ray psses through the centre of curvature of a spherical mirror, the reflected ray will

1. pass through the pole

2. pass through the centre of curvature

3. retrace its path

4. be parallel to the principal axis

Choose the only wrong statement from the following

1. a convex mirrir forms virtual images for all positions of the object.

2. a concave mirror forms real images for all positions of the object.

3. a concave mirror, if suitably placed in front of an object, can form a unity

4. the magnification produced by a convex mirror is alwys less than unity.

To form an image twice the size of the object, using a convex lens of focal length 20 cm, the object distance must be

1. < 20 cm

2. >20 cm

3. <20 cm and between 20 cm and 40 cm

4. cannot say

The refective index of dense flint lass is 1.65 and for alcohol, it is 1.36 with respect to air, then the refrective index of the dense flint glass with respect to alcohol is

1. 1.31

2. 1.22

3. 1.11

4. 1.01

Refractive index of diamond with erspect to glass is 1.6 and the absolute refractive index of glass is 1.5, then the absolute refractive index of diamond is

1. 1.4

2. 2.4

3. 3.4

4. 4.4

Power of a convex lens of focal length 50 cm is

1. -2D

2. -0.5D

3. +2D

4. +0.5D

In the case refraction of light from a rectangular glass slab, if i be the angle of incidence and e be the angle of emerfence, then

1. e=i

2. e<i

3. e>i

4. i$\ne $e

Which of the following lenses, would you prefer to use while reading small letters found in a dictionary?

1. A convex lens of focal length 50 cm

2. A concave lens of local length 50 cm

3. A concave lens of focal length 5 cm

4. A convex lens of focal length 5 cm

How will the image formed by a conavex lens be affected if the upper half of the lens is wrapped with a black paper?

1. the size of the image is reduced to one-half

2. the upper half of the image will be absent

3. the brightness of the image is reduced

4. there will be no effect

If f is focal length of the lens, then the power of a lens equal to

1. $\frac{100}{f\left(cm\right)}$

2. $\frac{10}{f\left(cm\right)}$

3. $\frac{100}{f\left(cm\right)}$

4. $\frac{1}{100f\left(cm\right)}$

a ray of light travelling inside a rectangular glass block of refractive index $\sqrt{2}$ is incident on the glass-air surface at an angle of incidence of ${45}^{\xb0}$. The refractive index of air is one. Under these conditions of the ray

1. will emerge into the air without any deviation

2. will be reflected back into the glass

3. will be absorbed

4. will emerge into the air with an angle of refraction equal to ${90}^{\xb0}$

A concave lens of a focal length forms an image which is n times the size of the object. The distance of the object from the lens is

1. (1-n)f

2. (1+n)f

3. $\left(\frac{1+n}{n}\right)f$

4. $\left(\frac{1-n}{n}\right)f$

A layered lens is made of two types of transparent materials indicated by different shades. A point object is placed on its axis the object will form

1. 1image

2. 2 images

3. 3 images

4. 9 images

Even in absolutely clear water, a driver cannot see very clearly

1. because rays of light get diffuesd

2. because velocity of light is reduced in water

3. because of ray of light passing through the water makes it tubrid

4. because the focal length of the eye lens in water gets changed and the image is no longer focused sharply on the retina

An object AB is placed in front of a convex lens at its principal focus as shown in figure below.

Which of the ray diagram below correctly depicts the defraction through the lens L.

1.

2.

3.

4.

With regard to refraction which of the following statement is false.

1. It is a change in direction of light when it passes from one transparent medium into another of different optical density

2. Lighgt is deviated away from the normal when it enters an optically dense medium from a less dense medium

3. the velocity of light is changed during refraction

4. the wavelength of the light is changed during refraction

A ray of light travelling in air is incident on the plane of a transparent medium. The angle of incident is ${45}^{\xb0}$ and that of refraction is ${30}^{\xb0}$. Find the refractive index of the medium.

1. 2

2. $\frac{1}{\sqrt{2}}$

3. 1

4. $\sqrt{2}$

How many images of himself does an observer see of two adjacent walls and the ceilling of a rectangular room are mirror surfaced?

1. 6

2. 7

3. 3

4. 5

A man 180 cm high stands in front of a plane mirror. His eyes are at a height of 172 cm from th floor. Then to see his full image for minimum length of mirror, the lower end of the mirror should be placed at a height of

1. 86 cm from the floor

2. 94 cm from the floor

3. 4 cm from the floor

4. 8 cm from the floor

The image of an object placed on the principal axis of a concave mirror of focal length 12 cm is formed at a point which is 10 cm more distant from the mirror than the object. The magnification of the image is

1. 2

2. 1.5

3. 1

4. 2.5

A concave spherical mirror forms a 40 cm high real image of an object whose height is 10 cm. The radius of the mirror is 60 cm. Find the distance from the object to its image.

1. 90 cm

2. 112.5 cm

3. 97.5 cm

4. 75 cm

A candle flame 3 cm high is placed at a distance of 3 m from a wall. HOw far from the wall must a cancave mirror be placed in order that it may form an image to the flame 9 cm high on the wall?

1. 450 cm

2. 150 cm

3. 225 cm

4. 300 cm

At what distance from a concave mirror of focal length 10 cm must an object be placed in order that an image double its size may be obtained?

1. Either 5 cm or 15 cm

2. At 10 cm

3. 5 cm

4. 15 cm only

The sun subtends an angle of half a degree at the pole of a conacave mirror which has a radius of curavture of 15 m. Then the size (diameter) of the image of the sun formed by the concave mirror is

1. 3.5 cm

2. 13.1 cm

3. 7.5 cm

4. 6.55 cm

Two vertical plane mirrors are inclined at an angle of ${60}^{\xb0}$, with each other. A ray of light travelling horizontally is reflected first from one mirror and then from the other mirror. Then the resultant deviation is

1. ${180}^{\xb0}$

2. ${240}^{\xb0}$

3. ${60}^{\xb0}$

4. ${120}^{\xb0}$

Light travels from the air into glass of refractive index 1.5. The time taken by the light to travel through a piece of glass of 50 cm thickness is

1. $2.25s$

2. $2.25\times {10}^{-7}s$

3. $2.5\times {10}^{-8}s$

4. $2.5\times {10}^{-9}s$

Two thin lenses of power, +3.5 D and -2.5 D are placed in contact, then the power and focal length of the lens combination is

1. + 1D, + 100 cm

2. + 2D, + 150 cm

3. + 1D, + 200 cm

4. + 2D, + 100 cm

A ray of light travelling from air enters a liquid at an angle of ${45}^{\xb0}$ with the normal. If the corresponding angle of refraction is ${30}^{\xb0}$, then the refractive index of the liquid with respect to air is

1. 1.44

2. 1.41

3. 1.21

4. 1.45

White light is incident on the interface of glass and air as shown in the figure. If green light is just totally internally reflected then the emerging ray in air contains

1, yellow, orange and red

2. violet, indigo and blue

3. all colours

4. all colours except green

A ray of light from a denser medium strikes a rare medium of angle of incidence i as shown in figure. The reflected and refracted rays make an angle ${90}^{\xb0}$ with each other. The angles of reflection and refraction are r and r'. The critical angle is

1. ${\mathrm{sin}}^{-1}(\mathrm{tan}r)$

2. ${\mathrm{sin}}^{-1}(\mathrm{tan}i)$

3. ${\mathrm{sin}}^{-1}(\mathrm{tan}r\text{'})$

4. ${\mathrm{tan}}^{-1}(\mathrm{tan}i)$

a point source of light is placed 4 m below the surface of water of refractive index 5/3. The minimum dimeter of a disc, which should placed over the source, on the surface of water to cut off all light coming out of water is

1. 1 m

2. 4 m

3. 3 m

4. 6 m

The distance between object and the screen is D. Real images of an object are formed on the screen for two positions of a lens seperated by a distance d. The ratio between the sizes of two images will be

1. D/d

2. ${\mathrm{D}}^{2}/{\mathrm{d}}^{2}$

3. ${\left(\mathrm{D}-\mathrm{d}\right)}^{2}/{\left(D+d\right)}^{2}$

4. $\sqrt{\left(\mathrm{D}/\mathrm{d}\right)}$

A convex lens A of focal length 20 cm and a concave lens B of focal length 5 cm are kept along the same axis with a distance d between them. If a parallel beam of light falling on A leaves B as a parallel beam, then the distance d in cm will be

1. 25

2. 15

3. 30

4. 50

a thin lens has focal length f, and its aperture has diameter d. It forms an image of intensity I. Now, the central part of the aperature up to diameter d/2 is blocked by an opaque paper. The focal length and image intensity will change to

1. f/2 and I/2

2. f and I/4

3. 3f/4 and I/2

4. f and 3I/4

An object is placed in front of a screen and a convex lens is placed at a position such that the size if the image formed is 9 cm. When the lens is shifted through a distance of 20 cm, the size of the image becomes 1 cm. The focal length of the lens and the size of the object are respectively,

1. 7.5 cm and 3.5 cm

2. 7.5 cm and 4 cm

3. 6 cm and 3 cm

4. 7.5 cm and 3 cm

Concave and convex lenses are placed touching each other. The ratio of magnitudes of their power is 2:3. The focal length of the system is 30 cm. Then the focal lengths of individual lenses are

1. -75 cm, 50 cm

2. -15 cm, 10 cm

3. 75 cm, 50 cm

4. 75 cm, -50 cm

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