Q. No.A biconvex lens has power \(P.\) It is cut into two symmetrical halves by a plane containing the principal axis. The power of one part will be:
1.
\(0\)
2.
\(\dfrac{P}{2}\)
3.
\(\dfrac{P}{4}\)
4.
\(P\)
A ray of light is directed toward a corner reflector as shown. The incident ray makes an angle of \(22^\circ\)
| 1. | \(22^\circ\) | 2. | \(68^\circ\) |
| 3. | \(44^\circ\) | 4. | \(34^\circ\) |
A convex lens is used to form an image of an object on a screen. If the upper half of the lens is blackened so that it becomes opaque, then:
| 1. | only half of the image will be visible. |
| 2. | the image position shifts towards the lens. |
| 3. | the image position shifts away from the lens. |
| 4. | the brightness of the image reduces. |
A ray of white light is incident on a spherical water drop whose centre is \(\mathrm{C}\) as shown below. When observed from the opposite side, the emergent light:
| 1. | will be white and will emerge without deviating. |
| 2. | will be internally reflected. |
| 3. | will split into different colours such that the angles of deviation will be different for all colours. |
| 4. | will split into different colours such that the angles of deviation will be the same for all colours. |
A student studying the similarities and differences between a camera and the human eye makes the following observations:
| (I) | both the eye and the camera have convex lenses. |
| (II) | in order to focus, the eye lens expands or contracts while the camera lens moves forward or backward. |
| (III) | the camera lens produces upside-down real images while the eye lens produces only upright real images. |
| (IV) | a screen in the camera is equivalent to the retina in the eyes. |
| (V) | a camera adjusts the amount of light entering it by adjusting the aperture of the lens. In the eye, the cornea controls the amount of light. |
The correct statements are:
| 1. | only (I), (II), (IV) |
| 2. | only (I), (III), (V) |
| 3. | only (I), (II), (IV), (V) |
| 4. | all of these |
Pick the wrong statement in the context with a rainbow.
| 1. | Rainbow is a combined effect of dispersion, refraction, and reflection of sunlight. |
| 2. | When the light rays undergo two internal reflections in a water drop, a secondary rainbow is formed. |
| 3. | The order of colors is reversed in the secondary rainbow. |
| 4. | An observer can see a rainbow when his front is towards the sun. |
For a normal eye, the cornea of the eye provides a converging power of \(40~\text{D}\) and the least converging power of the eye lens behind the cornea is \(20~\text{D}\). Using this information, the distance between the retina and the cornea-eye lens can be estimated to be:
1. \(2.5~\text{cm}\)
2. \(1.67~\text{cm}\)
3. \(1.5~\text{cm}\)
4. \(5~\text{cm}\)
The angle of a prism is \(A\). One of its refracting surfaces is silvered. Light rays falling at an angle of incidence \(2{A}\) on the first surface return back through the same path after suffering reflection at the silvered surface. The refractive index \(\mu,\) of the prism, is:
1. \(2\text{sin}A\)
2. \(2\text{cos}A\)
3. \(\dfrac{1}{2}\text{cos}A\)
4. \(\text{tan}A\)
If the focal length of the objective lens is increased then the magnifying power of:
| 1. | microscope will increase but that of the telescope decrease. |
| 2. | microscope and telescope both will increase. |
| 3. | microscope and telescope both will decrease. |
| 4. | microscope will decrease but that of the telescope will increase. |
The prism will:
| 1. | separate the blue colour part from the red and green colour. |
| 2. | separate all three colours from one another. |
| 3. | not separate the three colours at all. |
| 4. | separate the red colour part from the green and blue colours. |
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