On account of the disruption in education due to the corona pandemic, we're opening up our platform for teachers, free of cost. Know More →

JEE Main

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

Select Subject

Physics

Chemistry

Mathematics

Optics

Correct Marks 4

Incorrectly Marks -1

Q 1. A concave mirror of focal length {tex} f {/tex} produces an image {tex} n {/tex} times the size of the object. If the image is real then the distance of the object from the mirror is

A

{tex} ( n - 1 ) f {/tex}

B

{tex} \frac { ( n - 1 ) } { n } f {/tex}

{tex} \frac { ( n + 1 ) } { n } f {/tex}

D

{tex} ( n + 1 ) f {/tex}

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 2. A spherical surface of radius of curvature {tex} R {/tex} separates air (refractive index 1.0{tex} ) {/tex} from glass (refractive index 1.5.) The centre of curvature is in the glass. A point object {tex} P {/tex} placed in air is found to have a real image {tex} Q {/tex} in the glass. The line {tex} P Q {/tex} cuts the surface at a point {tex} O {/tex}, and {tex} P O = O Q . {/tex} The distance {tex} P O {/tex} is equal to

5{tex} R {/tex}

B

3{tex} R {/tex}

C

2{tex} R {/tex}

D

1.5{tex} R {/tex}

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 3. A ray of light falls normally on a refracting face of a prism of refractive index {tex} 1.5 . {/tex} If the ray just fails to emerge from the prism. Then the angle of prism is

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

B

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

C

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

D

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

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 4. A ray of light passes through four transparent media with refractive indices {tex} \mu _ { 1 } , \mu _ { 2 } , \mu _ { 3 } , {/tex} and {tex} \mu _ { 4 } {/tex} as shown in the Fig. The surfaces of all media are parallel. If the emergent ray {tex} C D {/tex} is parallel to the incident ray {tex} A B , {/tex} then

A

{tex} \mu _ { 1 } = \mu _ { 2 } {/tex}

B

{tex} \mu _ { 2 } = \mu _ { 3 } {/tex}

C

{tex} \mu _ { 3 } = \mu _ { 4 } {/tex}

{tex} \mu _ { 4 } = \mu _ { 1 } {/tex}

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 5. Two plane mirrors {tex} A {/tex} and {tex} B {/tex} are aligned parallel to each other as shown in Fig. A light ray is incident at an angle of {tex} 30 ^ { \circ } {/tex} at a point just inside one end of {tex} A {/tex}. The plane of incidence coincides with the plane of the Fig. The maximum number of times the ray undergoes reflections (including the first one) before it emerges out is

A

28

30

C

32

D

34

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 6. An object 1{tex} \mathrm { cm } {/tex} tall is placed in front of a mirror at a distance of 4{tex} \mathrm { cm } . {/tex} In order to produce an upright image of 3{tex} \mathrm { cm } {/tex} height, one needs a

A

convex mirror of radius of curvature {tex} 12 \mathrm { cm } . {/tex}

concave mirror of radius of curvature {tex} 12 \mathrm { cm } . {/tex}

C

concave mirror of radius of curvature {tex} 4 \mathrm { cm } . {/tex}

D

plane mirror of height {tex} 12 \mathrm { cm } . {/tex}

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 7. Light travels through a glass plate of thickness {tex} t {/tex} and having refractive index {tex} \mu {/tex}. If {tex} c {/tex} be the velocity of light in vacuum, the time taken by the light to travel this thickness of glass is

A

{tex} \frac { t } { \mu c } {/tex}

B

{tex} t \mu c {/tex}

{tex} \frac { \mu t } { c } {/tex}

D

{tex} \frac { t c } { \mu } {/tex}

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 8. A ray of light strikes a glass plate at an angle of {tex} 60 ^ { \circ } {/tex} with the vertical. If the reflected and refracted rays are perpendicular to each other, the refractive index of glass is

A

{tex} \frac { \sqrt { 3 } } { 2 } {/tex}

B

{tex} \frac { 3 } { 2 } {/tex}

C

{tex} \frac { 1 } { 2 } {/tex}

{tex} \sqrt { 3 } {/tex}

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 9. An optically active compound

Rotates the plane polarized light

B

Changes the direction of polarized light

C

Do not allow plane polarized light to pass through

D

None of the above

Correct Marks 4

Incorrectly Marks -1

Q 10. The principle of optical fibre is

A

Diffraction

B

Polarization

C

Interference

Total internal reflection

Correct Marks 4

Incorrectly Marks -1

Q 11. A beam of light starting from point {tex} A {/tex} reflects from a mirror {tex} M {/tex} and forms an image at {tex} B {/tex} as shown in the same horizontal plane as {tex} A {/tex}. For small angle of incidence {tex} i , A B {/tex} is equal to

A

{tex} i D {/tex}

2{tex} i D {/tex}

C

4{tex} i D {/tex}

D

{tex} i D / 2 {/tex}

Correct Marks 4

Incorrectly Marks -1

Q 12. In Young's double slit experiment, the width of one slit is double that of the other. The ratio of intensity of a bright band to that of a dark band in the interference pattern will be

A

{tex} 2 : 1 {/tex}

B

{tex} 3 : 1 {/tex}

C

{tex} 6 : 1 {/tex}

{tex} 9 : 1 {/tex}

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 13. The critical angle of a medium is {tex} \sin ^ { - 1 } ( 3 / 5 ) . {/tex} The polarizing angle of the medium will be

A

{tex} \sin ^ { - 1 } ( 4 / 5 ) {/tex}

{tex} \tan ^ { - 1 } ( 5 / 3 ) {/tex}

C

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

D

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

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 14. A glass prism of refractive index {tex}1.5{/tex} is immersed in water {tex} ( \mu = 4 / 3 ) . {/tex} A light beam incident normally on the face {tex} A B {/tex} is totally reflected to reach the face {tex} B C , {/tex} if

{tex} \sin \theta \geq \frac { 8 } { 9 } {/tex}

B

{tex} \sin \theta \leq \frac { 2 } { 3 } {/tex}

C

{tex} \sin \theta = \frac { 4 } { 5 } {/tex}

D

{tex} \frac { 2 } { 3 } < \sin \theta < \frac { 8 } { 9 } {/tex}

Explanation


Correct Marks 4

Incorrectly Marks -1

Q 15. An object is placed at a distance of 3{tex} f {/tex} from a convex lens of focal length {tex} f . {/tex} A slab of refractive index {tex} \mu {/tex} is placed in between lens and object. The image of the object will be formed nearest to the object if thickness of the slab is

A

{tex} f {/tex}

B

2{tex} f {/tex}

C

{tex} \frac { f } { \mu - 1 } {/tex}

{tex} \frac { \mu f } { \mu - 1 } {/tex}

Correct Marks 4

Incorrectly Marks -1

Q 16. A ray of light falls on a prism {tex} A B C ( A B = B C ) {/tex} and travels as shown in Fig. The refractive index of the prism material should be greater than

A

4{tex} / 3 {/tex}

{tex} \sqrt { 2 } {/tex}

C

{tex} 1.5 {/tex}

D

{tex} \sqrt { 3 } {/tex}

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 17. On introducing a thin sheet of mica (thickness {tex} 12 \times {/tex} {tex} 10 ^ { - 5 } \mathrm { cm } {/tex} ) in path of one of the interfering beams in Young's double slit experiment, the central fringe is shifted through a distance equal to the spacing between successive bright fringes. The refractive index of mica is (wavelength of light used {tex} \lambda = 6 \times 10 ^ { - 5 } \mathrm { cm } {/tex} )

A

{tex} 1.33 {/tex}

{tex} 1.5 {/tex}

C

{tex}2.5{/tex}

D

{tex}1.478{/tex}

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 18. Focal length of an equiconvex lens is {tex} 20 \mathrm { cm } . {/tex} If we cut it once perpendicular to principle axis, and then along principal axis, then focal length of each part will be

A

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

B

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

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

D

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

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 19. We have two equilateral prisms {tex} A {/tex} and {tex} B . {/tex} They are made of materials having refractive index 1.5 and 1.6. For minimum deviation, incident angle will be

Small for prism {tex} A {/tex}

B

Small for prism {tex} B {/tex}

C

Equal for both the prisms

D

Can't be predicted

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 20. A thin plano-convex glass lens {tex} ( \mu = 1.5 ) {/tex} has its plane surface silvered, and {tex} R {/tex} is the radius of curvature of curved part, then which of the following ray diagram is true for an object placed at {tex} O ? {/tex}

B

C

D

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 21. A fish looking up through the water sees the outside world contained in a circular horizon. If the refractive index of water is {tex} 4 / 3 {/tex} and

the fish is {tex} 12 \mathrm { cm } {/tex} below the surface, the radius of this circle in {tex} \mathrm { cm } {/tex} is

A

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

B

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

C

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

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

Explanation







Correct Marks 4

Incorrectly Marks -1

Q 22. To demonstrate the phenomenon of interference, we require two sources which emit radiation

A

of nearly the same frequency

B

of the same frequency

C

of different wavelengths

of the same frequency and having a definite phase relationship

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 23. To get three images of a single object, one should have two plane mirrors at an angle of

A

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

{tex} 90 ^ { \circ } {/tex}

C

{tex} 120 ^ { \circ } {/tex}

D

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

Explanation



Correct Marks 4

Incorrectly Marks -1

Q 24. 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

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

B

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

C

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

D

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

Explanation







Correct Marks 4

Incorrectly Marks -1

Q 25. A thin glass (refractive index 1.5) lens has optical power of- {tex}5D {/tex} in air. Its optical power in a liquid medium with refractive index 1.6 will be

A

{tex} - 1 D {/tex}

{tex}1 D {/tex}

C

{tex} - 25 D {/tex}

D

{tex}25 D {/tex}

Explanation