# NEET > Optics

Explore popular questions from Optics for NEET. This collection covers Optics previous year NEET questions hand picked by popular teachers.

Physics
Chemistry
Biology

Q 1.

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Incorrect-1

A double convex lens is made of glass which has its refractive index 1.45 for violet rays and 1.50 for red rays. If the focal length for violet ray is {tex} 20 \mathrm { cm } , {/tex} the focal length for red ray will be

A

9{tex} \mathrm { cm } {/tex}

18{tex} \mathrm { cm } {/tex}

C

20{tex} \mathrm { cm } {/tex}

D

22{tex} \mathrm { cm } {/tex}

##### Explanation Q 2.

Correct4

Incorrect-1

If the refractive index of the material of a prism is {tex} \cot \frac { \mathrm { A } } { 2 } {/tex} and the angle of prism is {tex} \mathrm { A } {/tex} , then angle of minimum deviation is

{tex} \pi - 2 A {/tex}

B

{tex} \pi - A {/tex}

C

{tex} \frac { \pi } { 2 } - 2 \mathrm { A } {/tex}

D

{tex} \frac { \pi } { 2 } - A {/tex}

##### Explanation Q 3.

Correct4

Incorrect-1

If two {tex} + 5 {/tex} diopter lenses are mounted at some distance apart, the equivalent power will always be negative if the distance is

greater than 40{tex} \mathrm { cm } {/tex}

B

equal to 40{tex} \mathrm { cm } {/tex}

C

equal to 10{tex} \mathrm { cm } {/tex}

D

less than 10{tex} \mathrm { cm } {/tex}

##### Explanation Q 4.

Correct4

Incorrect-1

Refraction of light from air to glass and from air to water are shown in figure (i) and figure (ii) below. The value of the angle {tex} \theta {/tex} in the case of refraction as shown in figure (iii) will be A

{tex} 30 ^ { \circ } {/tex}

{tex} 35 ^ { \circ } {/tex}

C

{tex} 60 ^ { \circ } {/tex}

D

{tex} 41 ^ { \circ } {/tex}

##### Explanation  Q 5.

Correct4

Incorrect-1

A fish looking up through the water sees the outside world contained in a circular horizon. If the refractive index of water is {tex} \frac { 4 } { 3 } {/tex} and the fish is 12{tex} \mathrm { cm } {/tex} below the surface, the radius of this circle in {tex} \mathrm { cm } {/tex} is

A

36{tex} \sqrt { 5 } {/tex}

B

4{tex} \sqrt { 5 } {/tex}

C

36{tex} \sqrt { 7 } {/tex}

36{tex} / \sqrt { 7 } {/tex}

##### Explanation Q 6.

Correct4

Incorrect-1

If {tex} f _ { V } {/tex} and {tex} f _ { R } {/tex} are the focal lengths of a convex lens for violet and red light respectively and {tex} F _ { V } {/tex} and {tex} F _ { R } {/tex} are the focal lengths of concave lens for violet and red light respectively, then we have

{tex} f _ { V } < f _ { R } {/tex} and {tex} F _ { V } > F _ { R } {/tex}

B

{tex} f _ { V } < f _ { R } {/tex} and {tex} F _ { V } < F _ { R } {/tex}

C

{tex} f _ { V } > f _ { R } {/tex} and {tex} F _ { V } > F _ { R } {/tex}

D

{tex} f _ { V } > f _ { R } {/tex} and {tex} F _ { V } < F _ { R } {/tex}

##### Explanation Q 7.

Correct4

Incorrect-1

Spherical aberration in a lens:

A

is minimum when most of the deviation is at first surface

B

is minimum when most of the deviation is at the second surface

is minimum when the total deviation is equally distributed over the two surfaces

D

does not depend on the above considerations

##### Explanation Q 8.

Correct4

Incorrect-1

A rod of length 10{tex} \mathrm { cm } {/tex} lies along the principal axis of a concave mirror of focal length 10{tex} \mathrm { cm } {/tex} in such a way that its end closer to the pole is 20{tex} \mathrm { cm } {/tex} away from the mirror. The length of the image is:

A

10{tex} \mathrm { cm } {/tex}

B

15{tex} \mathrm { cm } {/tex}

C

2.5{tex} \mathrm { cm } {/tex}

5{tex} \mathrm { cm } {/tex}

##### Explanation  Q 9.

Correct4

Incorrect-1

A telescope consists of two thin lenses of focal lengths, 0.3 {tex} \mathrm { m } {/tex} and 3{tex} \mathrm { cm } {/tex} respectively. It is focused on moon which subtends an angle of {tex} 0.5 ^ { \circ } {/tex} at the objective. Then the angle subtended at the eye by the final image will be

{tex} 5 ^ { 0 } {/tex}

B

{tex} 0.25 ^ { \circ } {/tex}

C

{tex} 0.5 ^ { \circ } {/tex}

D

{tex} 0.35 ^ { \circ } {/tex}

##### Explanation Q 10.

Correct4

Incorrect-1

The layered lens as shown is made of two types of transparent materials-one indicated by horizontal lines and the other by vertical lines. The number of images formed of an object will be A

1

2

C

3

D

6

##### Explanation Q 11.

Correct4

Incorrect-1

A man's near point is 0.5{tex} \mathrm { m } {/tex} and far point is {tex} 3 \mathrm { m } . {/tex} Power of spectacle lenses required for (i) reading purposes, (ii) seeing distant objects, respectively, are

A

{tex} - 2 \mathrm D \ and +3 \mathrm D {/tex}

B

{tex} + 2 \mathrm { D } {/tex} and {tex} - 3 \mathrm { D } {/tex}

{tex} + 2 \mathrm { D } {/tex} and {tex} - 0.33 \mathrm { D } {/tex}

D

{tex} - 2 \mathrm { D } {/tex} and {tex} + 0.33 \mathrm { D } {/tex}

##### Explanation Q 12.

Correct4

Incorrect-1

A ray of light falls on a transparent glass slab of refractive index {tex} 1.62 . {/tex} If the reflected ray and the refracted ray are mutually perpendicular, the angle of incidence is

{tex} \tan ^ { - 1 } ( 1.62 ) {/tex}

B

{tex} \tan ^ { - 1 } \left( \frac { 1 } { 1.62 } \right) {/tex}

C

{tex} \tan ^ { - 1 } ( 1.33 ) {/tex}

D

{tex} \tan ^ { - 1 } \left( \frac { 1 } { 1.33 } \right) {/tex}

##### Explanation  Q 13.

Correct4

Incorrect-1

A telescope has an objective of focal length 100{tex} \mathrm { cm } {/tex} and an eyepiece of focal length {tex} 5 \mathrm { cm } . {/tex} What is the magnifying power of the telescope when the final image is formed at the least distance of distinct vision?

A

20

24

C

28

D

32

##### Explanation Q 14.

Correct4

Incorrect-1

Which light rays undergoes two internal reflection inside a raindrop, which of the rainbow is formed?

A

Primary rainbow

Secondary rainbow

C

Both (a) and (b)

D

Can't say

##### Explanation Q 15.

Correct4

Incorrect-1

When a plane mirror is placed horizontally on a level ground at a distance of 60{tex} \mathrm { m } {/tex} from the foot of a tower, the top of the tower and its image in the mirror subtend an angle of {tex} 90 ^ { \circ } {/tex} at the eye. The height of the tower will be

A

30{tex} \mathrm { m } {/tex}

60{tex} \mathrm { m } {/tex}

C

90{tex} \mathrm { m } {/tex}

D

120{tex} \mathrm { m } {/tex}

##### Explanation Q 16.

Correct4

Incorrect-1

A parallel beam of light is incident on the surface of a transparent hemisphere of radius {tex} R {/tex} and refractive index 2.0 as shown in figure. The position of the image formed by refraction at the first surface is: A

{tex} R / 2 {/tex}

B

{tex} R {/tex}

2{tex} R {/tex}

D

3{tex} R {/tex}

##### Explanation Q 17.

Correct4

Incorrect-1

A lens made of glass whose index of refraction is 1.60 has a focal length of {tex} + 20 \mathrm { cm } {/tex} in air. Its focal length in water, whose refractive index is {tex} 1.33 , {/tex} will be

three times longer than in air

B

two times longer than in air

C

same as in air

D

None of these

##### Explanation Q 18.

Correct4

Incorrect-1

A compound microscope has an eye piece of focal length 10 {tex} \mathrm { cm } {/tex} and an objective of focal length {tex} 4 \mathrm { cm } . {/tex} Calculate the magnification, if an object is kept at a distance of 5{tex} \mathrm { cm } {/tex} from the objective so that final image is formed at the least distance vision {tex} ( 20 \mathrm { cm } ) : {/tex}

12

B

11

C

10

D

13

##### Explanation Q 19.

Correct4

Incorrect-1

For a prism kept in air it is found that for an angle of incidence {tex} 60 ^ { \circ } , {/tex} the angle of Prism {tex} \mathrm { A } {/tex} , angle of deviation {tex} \delta {/tex} and angle of emergence {tex} \mathrm { 'e' }{/tex} become equal. Then the refractive index of the prism is

1.73

B

1.15

C

15

D

1.33

##### Explanation Q 20.

Correct4

Incorrect-1

A person can see clearly only upto a distance of {tex} 30 \mathrm { cm } . {/tex} He wants to read a book placed at a distance of 50{tex} \mathrm { cm } {/tex} from his eyes. What is the power of the lens of his spectacles?

A

{tex} - 1.0 D {/tex}

{tex} - 1.33 \mathrm { D } {/tex}

C

{tex} - 1.67\mathrm D {/tex}

D

{tex} - 2.0 \mathrm { D } {/tex}

##### Explanation Q 21.

Correct4

Incorrect-1

An object is placed at a distance of 40{tex} \mathrm { cm } {/tex} in front of a concave mirror of focal length {tex} 20 \mathrm { cm } . {/tex} The image produced is

A

real, inverted and smaller in size

real, inverted and of same size

C

real and erect

D

virtual and inverted

##### Explanation Q 22.

Correct4

Incorrect-1

A vessel of depth x is half filled with oil of refractive index {tex}\mu_{1}{/tex} and the other half is filled with water of refractive index {tex}\mu_{2}{/tex}.The apparent depth of the vessel when viewed from above is

{tex} \frac { x \left( \mu _ { 1 } + \mu _ { 2 } \right) } { 2 \mu _ { 1 } \mu _ { 2 } } {/tex}

B

{tex} \frac { x \mu _ { 1 } \mu _ { 2 } } { 2 \left( \mu _ { 1 } + \mu _ { 2 } \right) } {/tex}

C

{tex} \frac { x \mu _ { 1 } \mu _ { 2 } } { \left( \mu _ { 1 } + \mu _ { 2 } \right) } {/tex}

D

{tex} \frac { 2 x \left( \mu _ { 1 } + \mu _ { 2 } \right) } { \mu _ { 1 } \mu _ { 2 } } {/tex}

##### Explanation  Q 23.

Correct4

Incorrect-1

The following figure shows refraction of light at the interface of three media Correct the order of optical density (d) of the media is A

{tex} d _ { 1 } > d _ { 2 } > d _ { 3 } {/tex}

B

{tex} d _ { 2 } > d _ { 1 } > d _ { 3 } {/tex}

C

{tex} d _ { 3 } > d _ { 3 } > d _ { 2 } {/tex}

{tex} d _ { 2 } > d _ { 3 } > d _ { 1 } {/tex}

##### Explanation Q 24.

Correct4

Incorrect-1

Light travels in two media {tex} A {/tex} and {tex} B {/tex} with speeds {tex} 1.8 \times {/tex} {tex} 10 ^ { 8 } \mathrm { m } \mathrm { s } ^ { - 1 } {/tex} and {tex} 2.4 \times 10 ^ { 8 } \mathrm { m } \mathrm { s } ^ { - 1 } {/tex} respectively. Then the critical angle between them is

A

{tex} \sin ^ { - 1 } \left( \frac { 2 } { 3 } \right) {/tex}

B

{tex} \tan ^ { - 1 } \left( \frac { 3 } { 4 } \right) {/tex}

C

{tex} \tan ^ { - 1 } \left( \frac { 2 } { 3 } \right) {/tex}

{tex} \sin ^ { - 1 } \left( \frac { 3 } { 4 } \right) {/tex}

##### Explanation Q 25.

Correct4

Incorrect-1

The refractive index of a glass is 1.520 for red light and 1.525 for blue light. Let {tex} D _ { 1 } {/tex} and {tex} D _ { 2 } {/tex} be angles of minimum deviation for red and blue light respectively in a prism of this glass. Then,

{tex} D _ { 1 } < D _ { 2 } {/tex}

B

{tex} D _ { 1 } = D _ { 2 } {/tex}

C

{tex} D _ { 1 } {/tex} can be less than or greater than {tex} D _ { 2 } {/tex} depending upon the angle of prism

D

{tex} D _ { 1 } > D _ { 2 } {/tex}

##### Explanation 