# JEE Main > Optics

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

Physics
Chemistry
Maths

Q 1.

Correct4

Incorrect-1

An astronomical telescope has a large aperture to

A

reduce spherical aberration

have high resolution

C

increase span of observation

D

have low dispersion.

##### Explanation

Q 2.

Correct4

Incorrect-1

If two mirrors are kept at {tex} 60 ^ { \circ } {/tex} to each other, then the number of images formed by them is

5

B

6

C

7

D

8

##### Explanation

Q 3.

Correct4

Incorrect-1

Electromagnetic waves are transverse in nature is evident by

polarization

B

interference

C

reflection

D

diffraction

##### Explanation

Q 4.

Correct4

Incorrect-1

Wavelength of light used in an optical instrument are {tex} \lambda _ { 1 } = 4000 {\textÅ} {/tex} and {tex} \lambda _ { 2 } = 5000 {\textÅ} , {/tex} then ratio of their respective resolving powers (corresponding to {tex} \lambda _ { 1 } {/tex} and {tex} \lambda _ { 2 } {/tex} )
is

A

{tex} 16 : 25 {/tex}

B

{tex} 9 : 1 {/tex}

C

{tex} 4 : 5 {/tex}

{tex} 5 : 4 {/tex}

##### Explanation

Q 5.

Correct4

Incorrect-1

Which of the following is used in optical fibres?

total internal reflection

B

scattering

C

diffraction

D

refraction.

##### Explanation

Q 6.

Correct4

Incorrect-1

Consider telecommunication through optical fibres. Which of the following statements is not true?

A

Optical fibres can be of graded refractive index

Optical fibres are subject to electromagnetic interference from outside

C

Optical fibres have extremely low transmission loss

D

Optical fibres may have homogeneous core with a suitable cladding.

##### Explanation

Q 7.

Correct4

Incorrect-1

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

Q 8.

Correct4

Incorrect-1

The image formed by an objective of a compound microscope is

A

virtual and diminished

B

real and diminished

real and enlarged

D

virtual and enlarged

##### Explanation

Q 9.

Correct4

Incorrect-1

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

Q 10.

Correct4

Incorrect-1

A light ray is incident perpendicularly to one face of a {tex} 90 ^ { \circ } {/tex} prism and is totally internally reflected at the glass-air interface. If the angle of reflection is {tex} 45 ^ { \circ } , {/tex} we conclude that the refractive index {tex} n {/tex}

A

{tex} n > \frac { 1 } { \sqrt { 2 } } {/tex}

{tex} n > \sqrt { 2 } {/tex}

C

{tex} n < \frac { 1 } { \sqrt { 2 } } {/tex}

D

{tex} n < \sqrt { 2 } {/tex}

##### Explanation

Q 11.

Correct4

Incorrect-1

A plano convex lens of refractive index 1.5 and radius of curvature {tex}30\, \mathrm { cm } {/tex} . Is silvered at the curved surface. Now this lens has been used to form the image of an object. At what distance from this lens an object be placed in order to have a real image of size of the object

A

{tex}60\, \mathrm { cm } {/tex}

B

{tex}30\, \mathrm { cm } {/tex}

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

D

{tex} 80\,\mathrm { cm } {/tex}

##### Explanation

Q 12.

Correct4

Incorrect-1

The angle of incidence at which reflected light is totally polarized for reflection from air to glass (refractive index {tex} n {/tex} ) , is

A

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

B

{tex} \sin ^ { - 1 } ( 1 / n ) {/tex}

C

{tex} \sin ^ { - 1 } ( n ) {/tex}

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

##### Explanation

Q 13.

Correct4

Incorrect-1

The maximum number of possible interference maxima for slit-separation equal to twice the wavelength in Young's double-slit experiment is

A

three

five

C

infinite

D

Zero

##### Explanation

Q 14.

Correct4

Incorrect-1

An electromagnetic wave of frequency {tex} v = 3.0\, \mathrm { MHz } {/tex} passes from vacuum into a dielectric medium with permittivity {tex} \epsilon = 4.0 . {/tex} Then

wave length is halved and frequency remains unchanged

B

wave length is doubled and frequency becomes half

C

wave length is doubled and the frequency remains unchanged

D

wave length and frequency both remain unchanged.

##### Explanation

Q 15.

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

{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

Q 16.

Correct4

Incorrect-1

Two point white dots are {tex} 1\,\mathrm { mm } {/tex} apart on a black paper. They are viewed by eye of pupil diameter {tex} 3\,\mathrm { mm } {/tex} . Approximately, what is the maximum distance at which these dots can be resolved by the eye? [ Take wavelength of light = {tex} 500 \mathrm { nm } {/tex}]

A

{tex} 1 \mathrm { m } {/tex}

{tex} 5\mathrm { m } {/tex}

C

{tex} 3\mathrm { m } {/tex}

D

{tex} 6\mathrm { m } {/tex}

##### Explanation

Q 17.

Correct4

Incorrect-1

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

Q 18.

Correct4

Incorrect-1

A Young's double slit experiment uses a monochromatic source. The shape of the interference fringes formed on a screen is

A

circle

B

hyperbola

C

parabola

straight line

##### Explanation

Q 19.

Correct4

Incorrect-1

If {tex} I _ { 0 } {/tex} is the intensity of the principal maximum in the single slit diffraction pattern, then what will be its intensity when the slit width is doubled?

{tex} 4I _ { 0 } {/tex}

B

{tex} 2I _ { 0 } {/tex}

C

{tex} \frac { I _ { 0 } } { 2 } {/tex}

D

{tex} I _ { 0 } {/tex}

##### Explanation

Q 20.

Correct4

Incorrect-1

When an unpolarized light of intensity {tex} I _ { 0 } {/tex} is incident on a polarizing sheet, the intensity of the light which does not get transmitted is

A

{tex} \frac { 1 } { 4 } I _ { 0 } {/tex}

{tex} \frac { 1 } { 2 } I _ { 0 } {/tex}

C

{tex} I _ { 0 } {/tex}

D

zero

##### Explanation

Q 21.

Correct4

Incorrect-1

The refractive index of a glass is {tex}1.520{/tex} for red light and {tex}1.525{/tex} 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

Q 22.

Correct4

Incorrect-1

In a Young's double slit experiment the intensity at a point where the path difference is {tex} \frac { \lambda } { 6 } {/tex}( {tex} \lambda {/tex} being the wavelength of light used) is {tex} I . {/tex} If {tex} I _ { 0 } {/tex} denotes the maximum intensity, {tex} \frac { I } { I _ { 0 } } {/tex} is equal to

{tex} \frac { 3 } { 4 } {/tex}

B

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

C

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

D

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

##### Explanation

Q 23.

Correct4

Incorrect-1

Two lenses of power {tex} - 15 D {/tex} and {tex} + 5 D {/tex} are in contact with each other. The focal length of the combination is

A

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

B

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

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

D

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

##### Explanation

Q 24.

Correct4

Incorrect-1

In an experiment, electrons are made to pass through a narrow slit of width {tex} 'd' {/tex} comparable to their de Broglie wavelength. They are detected on a screen at a distance {tex} 'D' {/tex} from the slit (see figure).

Which of the following graphs can be expected to represent the number of electrons {tex}' N' {/tex} detected as a function of the detector position {tex}'y'{/tex} ( y = 0 corresponds to the middle of the slit)

A

B

C

##### Explanation

Q 25.

Correct4

Incorrect-1

A student measures the focal length of a convex lens by putting an object pin at a distance '{tex} u {/tex}' from the lens and measuring the distance '{tex} v {/tex}' of the image pin. The graph between '{tex} u {/tex}' and '{tex} v{/tex}' plotted by the student should look like

A

B

D