RAY-OPTICS-AND-OPTICAL-INSTRUMENTS QUIZ 12

 

Ray Optics and Optical Instruments Quiz-12

Dear Readers,

As per analysis for previous years, it has been observed that students preparing for NEET find Physics out of all the sections to be complex to handle and the majority of them are not able to comprehend the reason behind it. This problem arises especially because these aspirants appearing for the examination are more inclined to have a keen interest in Biology due to their medical background. Furthermore, sections such as Physics are dominantly based on theories, laws, numerical in comparison to a section of Biology which is more of fact-based, life sciences, and includes substantial explanations. By using the table given below, you easily and directly access to the topics and respective links of MCQs. Moreover, to make learning smooth and efficient, all the questions come with their supportive solutions to make utilization of time even more productive. Students will be covered for all their studies as the topics are available from basics to even the most advanced. .

Q1. . A ray of light incident normally on one face of a right angled isosceles prism. It them grazes the hypotenuse. The refractive index of the material of the prism is

•   1.33
•   1.414
•   1.5
•  1.732

Solution
Refractive index, 𝜇 = 1 sin𝐶,Where 𝐶 is the critical angle Here, 𝐶 = 45° ∴ 𝜇 = 1/sin45° 𝑜𝑟 𝜇 = √2 𝑜𝑟 𝜇 = 1.414

Q2. Each quarter of a vessel of depth 𝐻 is filled with liquids of the refractive indices 𝑛1,𝑛2,𝑛3 and 𝑛4 from the bottom respectively. The apparent depth of the vessel when looked normally is

•   𝐻(𝑛1 + 𝑛2 + 𝑛3 + 𝑛4)/ 4
•   H(1/n_{2+1/n3+1/n4)/4}
•  (n₁+n₂+n₃+n₄)/4H
•  𝐻( 1/𝑛₁ + 1/𝑛₂ + 1/𝑛₃ + 1/𝑛₄ )/2

Solution
Apparent depth of bottom = (𝐻/4)/ 𝜇₁ + (𝐻/4)/ 𝜇₂ + (𝐻/4)/ 𝜇₃ + (𝐻/4)/ 𝜇₄ = 𝐻/4 ( 1/𝜇₁ + 1/𝜇₂ + 1/𝜇₃ + 1/𝜇₄ )

Q3.  In the formation of primary rainbow, the sunlight rays emerge at minimum deviation from rain-drop after

•    One internal reflection and one refraction
•   One internal reflection and two refraction
•    Two internal reflection and one refraction
•   Two internal reflection and one refraction

Solution
One internal reflection and two refraction

Q4.  Which of the following graphs is the magnification of a real image against the distance from the focus of a concave mirror

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Solution
For concave mirror 𝑚 = 𝑓/ 𝑓−𝑢 For real image 𝑚 = − 𝑓/(𝑢−𝑓) = − 𝑓/𝑥 = − 𝑓/(Distance of object from focus) ⇒ 𝑚 ∝ 1/𝑥 .

Q5. A triangular prism of glass is shown in the figure. A ray incident normally to one face is totally reflected, if 𝜃 = 5°. The index of refraction of glass is

•  Less than 1.41
•  Equal to 1.41
•  Greater than 1.41
•  None of the above

Solution
 For total internal reflection 𝜃 > 𝐶 ⇒ sin𝜃 > sin𝐶 ⇒ sin𝜃 > 1/𝜇 or 𝜇 > 1/sin𝜃 ⇒ 𝜇 > 1/sin45° ⇒ 𝜇 > √2 ⇒ 𝜇 > 1.41 .

Q6. 𝑃𝑄𝑅 is a right angled prism with other angles as 60° and 30°. Refractive index of prism is 1.5. 𝑃𝑄 has a thin layer of liquid. Light falls normally on the face 𝑃𝑅. For total internal reflection, maximum refractive index of liquid is

•   1.4
•  1.3
• 1.2
•  1.6

Solution
For 𝑇𝐼𝑅 at 𝑃𝑄; 𝜃 > 𝐶 From geometry of figure 𝜃 = 60°,𝑖.𝑒.,60° < 𝐶 ⇒ sin60 > sin𝐶 ⇒ √3/2 > 𝜇𝐿𝑖𝑞𝑢𝑖𝑑 𝜇Pr𝑖𝑠𝑚 ⇒ 𝜇𝐿𝑖𝑞𝑢𝑖𝑑 < √3/2 × 𝜇Pr𝑖𝑠𝑚 ⇒ 𝜇𝐿𝑖𝑞𝑢𝑖𝑑 < √3/2 × 1.5 ⇒ 𝜇𝐿𝑖𝑞𝑢𝑖𝑑 < 1.3

Q7. Which one of the following is not associated with total internal reflection

•   The mirage formation
•   Optical fiber communication
•   The glittering of diamond
•  Dispersion of light

Solution

Dispersion of light

Q8. As the position of an object (𝑢) reflected from a concave mirror is varied, the position of the image (𝑣) also varies. By letting the 𝑢 changes from 0 to +∞ the graph between 𝑣 versus 𝑢 will be

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Solution
At 𝑢 = 𝑓,𝑣 = ∞ At 𝑢 = 0,𝑣 = 0 (𝑖.𝑒. object and image both lies at pole) Satisfying these two conditions, only option (a) is correct

Q9. Dispersive power depends on the following

•  Material of the prism
•  Shape of the prism
•  Size of the prism
•  Size, shape and material of the prism

Solution
Material of the prism

Q10.  The communication using optical fibres is based on the principle of

•   Total internal reflection
•   Brewster angle
•   Polarization
• Resonance

Solution
The communication using optical fibres is based on the principle of total internal reflection