Refraction and Reflection MCQ Quiz in मल्याळम - Objective Question with Answer for Refraction and Reflection - സൗജന്യ PDF ഡൗൺലോഡ് ചെയ്യുക

Given:

Which of the following statements about the phenomenon of the primary rainbow formation by water droplets is/are correct?

1. It involves refraction and one internal reflection of sunlight.

2. It involves refraction of sunlight only.

3. It is formed as the inner bow.

4. It may involve more than one internal reflection as well as the refraction of sunlight.

Concept Used:

A primary rainbow is formed due to the refraction, internal reflection, and dispersion of light in water droplets. The light undergoes one internal reflection inside the droplet before emerging to form the primary rainbow.

Explanation:

Statement 1: Correct. A primary rainbow involves refraction and one internal reflection of sunlight.

Statement 2: Incorrect. It involves both refraction and internal reflection, not just refraction.

Statement 3: Correct. The primary rainbow is indeed formed as the inner bow.

Statement 4: Incorrect. The primary rainbow involves only one internal reflection, not more than one.

∴ The correct answer is option 1 (1 and 3).

Concept:

• The power of the lens, \(P=\frac{1}{f}\) where, f = focal length of the lens

Hypermetropia:

• Hypermetropia is also referred to as hyperopia or long-sightedness, or far-sightedness.
• Hypermetropia is the condition of the eyes where the image of a nearby object is formed behind the retina.
• Here, the light is focused behind the retina instead of focusing on the retina.

• Hypermetropia is mainly caused due to certain structural defects in the retina. Structural defects include:

  • Small-sized eye-ball
  • Non-circular lenses
  • The cornea is flatter than usual
• A convex lens is used for the correction of hypermetropia

Explanation:

Given,

power, P = +2 D,

So, focal length, \(f=\frac{1}{P}\)

\(f=\frac{100}{2}= 50~cm\)

​Therefore, the focal length is positive which is for a convex lens and a convex lens is used for the correction of hypermetropia. So, the person is suffering from hypermetropia.

Additional Information 
Myopia:

• Myopia or Nearsightedness occurs when the eye loses its ability to focus on far-off objects as the lenses do not possess a long focal length.
• Objects that are near are clearly visible to patients with this defect.
• As we know, from the reference for countless ray diagrams describing the functioning of the eye, when the light suffers higher refraction than usual, the eye would not be able to form an image for faraway objects.

• This eye defect is corrected with a concave lens.

Concept:

1. Binocular Vision: - Humans have two eyes placed slightly apart on the face. - This arrangement allows for binocular vision, where both eyes can view the same object from slightly different angles.
2. Depth Perception: - Binocular vision enables depth perception. - Depth perception is the ability to judge the distance of objects and perceive the world in three dimensions.
3. Stereopsis:- Stereopsis is the process by which the brain combines the two different images from each eye to create a three-dimensional understanding of a scene. - This combined image allows us to perceive the depth of objects relative to each other.
4. Spatial Awareness: - Having two eyes enhances spatial awareness and helps in better coordination and navigation through complex environments.
5. Visual Cues: - Depth perception involves several visual cues, including binocular disparity, convergence, and other monocular cues like size, texture, and shading.

Explanation:

• Humans have two eyes positioned apart to enhance their ability to perceive depth, which is a critical aspect of interacting with their environment.
• Each eye captures a slightly different image due to the different angles of view. The brain processes these two images to create a single three-dimensional representation of the scene.
• This process, known as stereopsis, allows us to perceive the relative positions of objects in three-dimensional space and to estimate distances accurately.
• Height, area, and length can be perceived with one eye; depth, however, is significantly enhanced by binocular vision, providing a sense of how far away objects are and their spatial relationships.

Conclusion:

The correct answer is Depth

Explanation:

• Statement I is correct because, when white light passes through a prism, it disperses into its constituent colors. Red light, having the longest wavelength, bends the least, while violet light, having the shortest wavelength, bends the most.
• As λred > λyellow > λviolet
• Statement II is also correct because the refractive index of a medium varies with the wavelength of light, leading to different bending angles for different colors (this phenomenon is called dispersion).
• A light ray with a longer wavelength bends less. 
• Statement II explains why red light bends less than yellow and violet.

∴ The correct option is 1

Concept:

• Soap bubbles appear colored due to a phenomenon known as thin-film interference, which is a result of light waves reflecting off both the outer and inner surfaces of the thin soap film and then interfering with each other.

Explanation:

• Interference is the process where two or more waves of the same type come together and combine to form a new wave. When light waves encounter a thin film like a soap bubble, some light waves are reflected off the outer surface while others pass through and are reflected off the inner surface.
• These reflected waves can then interfere with each other, either reinforcing or canceling each other out, depending on the thickness of the film and the angle of incidence of the light. This leads to the various colors seen in soap bubbles.
• So, the correct answer is 2) Interference.

 Additional Information

• The colors of a soap bubble are constantly changing because the thickness of the soap film is changing as the bubble drains under gravity and as water evaporates from the film.
• This means the path difference between the light waves reflecting off the outer and inner surfaces is also changing, leading to changing interference patterns.

Concept:

The focal length of a lens is given by

\({1\over f}\) = \([{μ_2 \over μ_1}-1][{1\over R_1}-{1\over R_2}]\)

where μ₁, μ₂, R₁ and R₂ are refractive indices and radii respectively.  

Calculation:

Given:

f1 = 20 cm

Focal length of the lens in air, μ1 = 1.5

Focal length of the lens in water, μ2 = 1.33

\({1\over f}\) = \([{μ_2 \over μ_1}-1][{1\over R_1}-{1\over R_2}]\)

\({1\over 20}\) = \([1.5 -1][{1\over R_1}-{1\over R_2}]\)

∴  \([{1\over R_1}-{1\over R_2}]\) = 0.1

\({1\over f'}\) = \([{μ_2 \over μ_1}-1][{1\over R_1}-{1\over R_2}]\)

= \([{1.5 \over 1.33}-1]\times 0.1\)

=  78.23 cm

The correct answer is option (1).

From graph it is clear that \(\tan 30^{o}=\dfrac{\sin r}{\sin i}\)

\(\Rightarrow \dfrac{1}{\sqrt{3}}=\dfrac{\sin r}{\sin i}=\dfrac{1}{\mu}\Rightarrow \mu=\sqrt{3}\)

Also \(v=\dfrac{c}{\mu}=nc\Rightarrow n=\dfrac{1}{\mu}=\dfrac{1}{\sqrt{3}}=(3)^{-1/2}\)

Concept:

In a double-slit experiment, the introduction of a glass plate in the path of one of the interfering beams causes a phase shift due to the change in the optical path length.

The optical path difference introduced by the glass plate is given by:

ΔL = (μ - 1) * t

Where:

• μ is the refractive index of the glass plate.
• t is the thickness of the glass plate.

The phase difference introduced by this optical path difference is:

Δφ =\( \frac{2πΔL}{λ}\)

Δφ \( = \frac{2π(μ - 1)t}{λ}\)

For the intensity at the central maximum to remain unchanged, the phase difference must correspond to a multiple of 2π, which means there is no shift in the central maximum:

Δφ = 2nπ

(where n = an integer)

Calculation:

Equating the phase difference to 2πn (for minimum thickness, ( n = 1)

⇒ \(\frac{2π(μ - 1)t}{λ} = 2π\)

The minimum thickness (t)

⇒ \(t = \frac{λ}{μ - 1}\)

⇒ μ = 1.4

⇒ t =\( \frac{λ}{1.4 - 1}\)

⇒  t = \(\frac{λ}{0.4}\) = 2.5λ

The minimum thickness of the glass plate is 2.5λ.

∴ The correct option is 1

The Correct answer is Both (A) and (R) are true and (R) is the correct explanation for (A).

Concept:

• Refraction of light: Refraction is the bending of light when it passes from one medium to another with a different refractive index. The refractive index is a measure of how much light slows down when passing through a medium. When light travels from a medium with a higher refractive index to a medium with a lower refractive index (such as water to air), it bends away from the normal (an imaginary line perpendicular to the surface).

Explanation:​

• The changes in refractive index, the light rays from the fish bend away from the normal (an imaginary line perpendicular to the water surface) as they exit the water and enter the air. This bending of light causes the rays to spread out more, making the fish appear larger than it actually is when viewed from above the water's surface.
• Larger appearance: The bending of light makes the fish's image appear higher than its actual position. As a result, the observer sees the top part of the fish (closer to the water's surface) first and then the lower part. This effect creates an elongated image of the fish, making it appear larger than its real size.
• Raised position: Since the light rays bend away from the normal, the apparent position of the fish is higher than its actual position. This is why the fish appears to be raised or lifted up relative to its actual location in the water.

Calculatiion:

δ_net = 0

(μ₁ – 1)A₁ – (μ2 – 1)A₂ = 0

(1.54 – 1)4 – (1.72 – 1)A₂ = 0

A₂ = 3°