Wave Optics | Physics JEE previous year questions with Solutions

Q 1 :
Which of the following phenomena is not explained by wave nature of light?

(A) reflection
(B) diffraction
(C) photoelectric effect
(D) interference
(E) polarization

Choose the most appropriate answer from the options given below: [2024]

E only
A, C only
B, D only
C only

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(4)

Photoelectric effect cannot be explained by wave nature of light. Reflection, diffraction, interference, and polarization are shown by wave nature of light.

Q 2 :
Two coherent monochromatic light beams of intensities I and 4I are superimposed. The difference between maximum and minimum possible intensities in the resulting beam is xl. The value of x is ______. [2024]

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(8) $I_{m a x} - I_{m i n} = x I$

$I_{m a x} = {(\sqrt{I} + \sqrt{4 I})}^{2} = 9 I$

$I_{m i n} = {(\sqrt{4 I} - \sqrt{I})}^{2} = I$

$9 I - I = x I$

$8 I = x I \Rightarrow x = 8$

Q 3 :
Light emerges out of a convex lens when a source of light is kept at its focus. The shape of wavefront of the light is [2024]

both spherical and cylindrical
plane
cylindrical
spherical

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(2)

Q 4 :
A transparent film of refractive index, 2.0 is coated on a glass slab of refractive index, 1.45. What is the minimum thickness of transparent film to be coated for the maximum transmission of Green light of wavelength 550 nm. [Assume that the light is incident nearly perpendicular to the glass surface.] [2025]

94.8 nm
68.7 nm
137.5 nm
275 nm

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(3)

For maximum transmission, reflection is zero.

$∴$ For green light there should be minima for interference of two reflected lights.

For transmitted green light to be maxima, reflected green should be minima.

$△ x = 2 μ_{0} t = n λ$

$\Rightarrow t = \frac{n λ}{2 μ_{0}}$

$∴ t_{\min} = \frac{λ}{2 μ_{0}} = \frac{550}{2 \times 2} = 137.5 nm$

Q 5 :
Which of the following phenomena can not be explained by wave theory of light? [2025]

Reflection of light
Diffraction of light
Refraction of light
Compton effect

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(4)

Compton effect refers to scattering of a photon by free electrons.

This phenomenon provides an evidence for particle nature of light.

Q 6 :
Width of one of the two slits in a Young's double slit interference experiment is half of the other slit. The ratio of the maximum to the minimum intensity in the interference pattern is: [2025]

$(2 \sqrt{2} + 1) : (2 \sqrt{2} - 1)$
$(3 + 2 \sqrt{2}) : (3 - 2 \sqrt{2})$
9 : 1
3 : 1

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(2)

$I \propto width$ $I_{\max} = {(\sqrt{I_{1}} + \sqrt{I_{2}})}^{2}$

$∴ I_{1} = I_{0}, I_{2} = 2 I_{0}$ $I_{\min} = {(\sqrt{I_{1}} - \sqrt{I_{2}})}^{2}$

$\frac{I_{\max}}{I_{\min}} = \frac{{(\sqrt{2} + 1)}^{2}}{{(\sqrt{2} - 1)}^{2}} \Rightarrow \frac{3 + 2 \sqrt{2}}{3 - 2 \sqrt{2}}$

Q 7 :
Two monochromatic light beams have intensities in the ratio 1 : 9. An interference pattern is obtained by these beams. The ratio of the intensities of maximum to minimum is [2025]

8 : 1
9 : 1
3 : 1
4 : 1

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(4)

$\frac{I_{m a x}}{I_{m i n}} = \frac{{(\sqrt{I_{1}} + \sqrt{I_{2}})}^{2}}{{(\sqrt{I_{1}} - \sqrt{I_{2}})}^{2}}$

$= \frac{{(1 + 3)}^{2}}{{(1 - 3)}^{2}} = \frac{16}{4} = 4$

Q 8 :
A monochromatic light of frequency $5 \times 10^{14}$ Hz travelling through air, is incident on a medium of refractive index '2'. Wavelength of the refracted light will be: [2025]

300 nm
600 nm
400 nm
500 nm

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(1)

Wave speed, $v = f λ$

As $μ$ = 2 therefore; speed $c \to \frac{c}{2}$

$λ_{medium} = \frac{c}{2 f} = \frac{3 \times 10^{8}}{2 \times 5 \times 10^{14}} = 3 \times 10^{- 7} m$

$= 3 \times 10^{- 7} \times 10^{9} nm = 300 nm$

Q 9 :
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R)

Assertion (A) : Refractive index of glass is higher than that of air.

Reason (R) : Optical density of a medium is directly proportionate to its mass density which results in a proportionate refractive index.

In the light of the above statements, choose the most appropriate answer from the options given below: [2025]

(A) is not correct but (R) is correct
Both (A) and (R) are correct and (R) is the correct explanation of (A)
(A) is correct but (R) is not correct
Both (A) and (R) are correct but (R) is not the correct explanation of (A)

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(3)

Speed of light $v = \frac{c}{μ}$

for air v $\approx$ c, for glass v < c so $μ_{g} > μ_{a}$

Refractive index has no relation with mass density because both have different meaning. Hence reason is incorrect.

It means (A) is correct but (R) is not correct.

Q 10 :
A thin transparent film with refractive index 1.4, is held on circular ring of radius 1.8 cm. The fluid in the film evaporates such that transmission through the film at wavelength 560 nm goes to a minimum every 12 seconds. Assuming that the film is flat on its two sides, the rate of evaporation is _________ $π \times 10^{- 13} m^{3} / s$ . [2025]

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(54)

Maxima condition, $2 μ t = n λ$

$\Rightarrow t = \frac{n λ}{2 μ} \Rightarrow t = \frac{λ}{2 μ}, \frac{2 λ}{2 μ}, . . .$

Minima condition, $2 μ t = \frac{(2 n - 1) λ}{2}$

$\Rightarrow t = \frac{(2 n - 1) λ}{4 μ} \Rightarrow t = \frac{λ}{4 μ}, \frac{3 λ}{4 μ}, . . .$

$△ t = \frac{2 λ}{4 μ}$

Rate of evaporation $= \frac{Area (△ t)}{Time} = 54 π \times 10^{- 13} m^{3} / s$

Topic Question Set

Q 1 :
Which of the following phenomena is not explained by wave nature of light?

(A) reflection
(B) diffraction
(C) photoelectric effect
(D) interference
(E) polarization

Choose the most appropriate answer from the options given below: [2024]

Q 2 :
Two coherent monochromatic light beams of intensities I and 4I are superimposed. The difference between maximum and minimum possible intensities in the resulting beam is xl. The value of x is ______. [2024]

0%

Q 3 :
Light emerges out of a convex lens when a source of light is kept at its focus. The shape of wavefront of the light is [2024]

Q 5 :
Which of the following phenomena can not be explained by wave theory of light? [2025]

Q 6 :
Width of one of the two slits in a Young's double slit interference experiment is half of the other slit. The ratio of the maximum to the minimum intensity in the interference pattern is: [2025]

Q 7 :
Two monochromatic light beams have intensities in the ratio 1 : 9. An interference pattern is obtained by these beams. The ratio of the intensities of maximum to minimum is [2025]

Q 8 :
A monochromatic light of frequency $5 \times 10^{14}$ Hz travelling through air, is incident on a medium of refractive index '2'. Wavelength of the refracted light will be: [2025]

0%

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Topic Question Set

Q 1 : Which of the following phenomena is not explained by wave nature of light? (A) reflection (B) diffraction (C) photoelectric effect (D) interference (E) polarization Choose the most appropriate answer from the options given below: [2024]

Q 2 : Two coherent monochromatic light beams of intensities I and 4I are superimposed. The difference between maximum and minimum possible intensities in the resulting beam is xl. The value of x is ______. [2024]

0%

Q 3 : Light emerges out of a convex lens when a source of light is kept at its focus. The shape of wavefront of the light is [2024]

Q 5 : Which of the following phenomena can not be explained by wave theory of light? [2025]

Q 6 : Width of one of the two slits in a Young's double slit interference experiment is half of the other slit. The ratio of the maximum to the minimum intensity in the interference pattern is: [2025]

Q 7 : Two monochromatic light beams have intensities in the ratio 1 : 9. An interference pattern is obtained by these beams. The ratio of the intensities of maximum to minimum is [2025]

Q 8 : A monochromatic light of frequency 5×1014 Hz travelling through air, is incident on a medium of refractive index '2'. Wavelength of the refracted light will be: [2025]

0%

Want Us to Email you About Special Offers & Updates?

Q 1 :
Which of the following phenomena is not explained by wave nature of light?

(A) reflection
(B) diffraction
(C) photoelectric effect
(D) interference
(E) polarization

Choose the most appropriate answer from the options given below: [2024]

Q 2 :
Two coherent monochromatic light beams of intensities I and 4I are superimposed. The difference between maximum and minimum possible intensities in the resulting beam is xl. The value of x is ______. [2024]

Q 3 :
Light emerges out of a convex lens when a source of light is kept at its focus. The shape of wavefront of the light is [2024]

Q 5 :
Which of the following phenomena can not be explained by wave theory of light? [2025]

Q 6 :
Width of one of the two slits in a Young's double slit interference experiment is half of the other slit. The ratio of the maximum to the minimum intensity in the interference pattern is: [2025]

Q 7 :
Two monochromatic light beams have intensities in the ratio 1 : 9. An interference pattern is obtained by these beams. The ratio of the intensities of maximum to minimum is [2025]

Q 8 :
A monochromatic light of frequency $5 \times 10^{14}$ Hz travelling through air, is incident on a medium of refractive index '2'. Wavelength of the refracted light will be: [2025]