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Q. No.Two thin lenses are of the same focal lengths \((f),\) but one is convex and the other one is concave. When they are placed in contact with each other, the equivalent focal length of the combination will be:
1. infinite
2. zero
3. \(f/4\)
4. \(f/2\)
Subtopic: Lenses |
62%
Level 2: 60%+
NEET - 2023
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A lens is made up of \(3\) different transparent media as shown in the figure. A point object \(O\) is placed on its axis beyond \(2f\). How many real images will be obtained on the other side?
| 1. | \(2\) | 2. | \(1\) |
| 3. | No image will be formed | 4. | \(3\) |
Subtopic: Lenses |
67%
Level 2: 60%+
NEET - 2023
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A horizontal ray of light is incident on the right-angled prism with prism angle \(6^\circ.\) If the refractive index of the material of the prism is \(1.5,\) then the angle of emergence will be:
| 1. | \(9^\circ\) | 2. | \(10^\circ\) |
| 3. | \(4^\circ\) | 4. | \(6^\circ\) |
Subtopic: Prisms |
63%
Level 2: 60%+
NEET - 2023
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Which set of colours would be observed in the air under the conditions depicted in the figure?
| 1. | yellow, orange, and red |
| 2. | blue, green, and yellow |
| 3. | orange, red, and violet |
| 4. | all of the above |
Subtopic: Total Internal Reflection |
75%
Level 2: 60%+
NEET - 2023
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An object is mounted on a wall. Its image of equal size is to be obtained on a parallel wall with the help of a convex lens placed between these walls. The lens is kept at distance \(x\) in front of the second wall. The required focal length of the lens will be:
| 1. | less than \(\dfrac x4\) |
| 2. | more than \(\dfrac x4\) but less than \(\dfrac x2\) |
| 3. | \(\dfrac x2\) |
| 4. | \(\dfrac x4\) |
Subtopic: Refraction at Curved Surface |
65%
Level 2: 60%+
NEET - 2023
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In the figure shown here, what is the equivalent focal length of the combination of lenses?
(Assume that all layers are thin)
(Assume that all layers are thin)
| 1. | \(-50~\text{cm}\) | 2. | \(40~\text{cm}\) |
| 3. | \(-40~\text{cm}\) | 4. | \(-100~\text{cm}\) |
Subtopic: Lens Makers' Formula |
52%
Level 3: 35%-60%
NEET - 2023
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Light travels a distance \(x\) in time \(t_1\) in air and \(10x\) in time \(t_2\) in another denser medium. What is the critical angle for this medium?
| 1. | \(\sin ^{-1}\left(\frac{10 t_1}{t_2}\right) \) | 2. | \(\sin ^{-1}\left(\frac{ t_2}{t_1}\right) \) |
| 3. | \(\sin ^{-1}\left(\frac{10 t_2}{t_1}\right) \) | 4. | \(\sin ^{-1}\left(\frac{ t_1}{10t_2}\right) \) |
Subtopic: Total Internal Reflection |
67%
Level 2: 60%+
NEET - 2023
Hints
An observer is using an astronomical refracting telescope to observe planets in normal adjustment. The focal lengths of the objective and eyepiece used in the telescope construction are \(20\text{m}\) and \(2\text{cm}\) respectively. Consider the following statements about the telescope:
The correct statements are:
| (A) | the distance between the objective and the eyepiece is \(20.02\text{m}.\) |
| (B) | the magnification of the telescope is \(-1000\). |
| (C) | the image of the planet is erect and diminished. |
| (D) | the aperture of the eyepiece is smaller than that of the objective. |
The correct statements are:
| 1. | A, B, and C | 2. | B, C, and D |
| 3. | C, D, and A | 4. | A, B, and D |
Subtopic: Telescope |
68%
Level 2: 60%+
NEET - 2022
Hints
During a cloudy day, a primary and a secondary rainbow may be created. Which of the following statement is correct?
| 1. | primary rainbow is due to double internal reflection and is formed above the secondary one. |
| 2. | primary rainbow is due to double internal reflection and is formed below the secondary one. |
| 3. | secondary rainbow is due to double internal reflection and is formed above the primary one. |
| 4. | secondary rainbow is due to a single internal reflection and is formed above the primary one. |
Subtopic: Total Internal Reflection |
68%
Level 2: 60%+
NEET - 2022
Hints
A beam of light is incident vertically on a glass slab of thickness \(1~\text{cm},\) and refractive index \(1.5.\) A fraction \(A\) is reflected from the front surface while another fraction \(B\) enters the slab and emerges after reflection from the back surface. The time delay between them is:
| 1. | \(10^{-10}~\text{s}\) | 2. | \(5\times 10^{-10}~\text{s}\) |
| 3. | \(10^{-11}~\text{s}\) | 4. | \(5\times 10^{-11}~\text{s}\) |
Subtopic: Refraction at Plane Surface |
59%
Level 3: 35%-60%
NEET - 2022
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