1.
The term “accommodation” as applied to the eye, refers to its ability to:
Correct Answer
C. Vary the focal length of the lens
Explanation
The term "accommodation" as applied to the eye refers to its ability to vary the focal length of the lens. This means that the eye can adjust the shape of the lens to focus on objects at different distances. When focusing on near objects, the lens becomes more rounded, increasing its refractive power. When focusing on distant objects, the lens becomes flatter, decreasing its refractive power. This adjustment in the lens shape allows the eye to maintain clear vision at different distances.
2.
A got his eye tested. The optician’s prescription for the spectacles reads:
Left eye: –3 D
Right eye: +3.50 D
The person is having a defect of vision called:
Correct Answer
B. Myopia
Explanation
The person is having a defect of vision called myopia. Myopia, also known as nearsightedness, is a condition where a person can see objects that are close to them clearly, but objects that are far away appear blurry. The optician's prescription indicates that the person's left eye has a power of -3 D, which means that the eye needs a concave lens to correct the vision. Similarly, the right eye has a power of +3.50 D, indicating the need for a convex lens to correct the vision. This prescription is typical for someone with myopia.
3.
How do you think that the eye change in order to focus on near or distant objects?
Correct Answer
C. The lens becomes thicker or thinner
Explanation
The lens in the eye changes its shape to focus on near or distant objects. When focusing on near objects, the lens becomes thicker, allowing it to refract light more strongly and bring the image into focus on the retina. Conversely, when focusing on distant objects, the lens becomes thinner, causing less refraction and allowing the image to be focused on the retina. This adjustment in the lens shape enables the eye to accommodate and provide clear vision at different distances.
4.
A man finds it difficult to read the odometer on the dashboard of the car but is able to clearly read a distant road sign. Which of the following statement is correct about this man?
Correct Answer
A. The near point of his eyes has receded away
Explanation
The man finding it difficult to read the odometer but being able to clearly read a distant road sign suggests that his near point has receded away. This means that the closest distance at which he can focus his eyes has increased, making it harder for him to see objects up close.
5.
A person cannot see the distant objects clearly (though he can see the nearby objects clearly). He is suffering from the defect of vision called:
Correct Answer
C. Myopia
Explanation
Myopia, also known as nearsightedness, is a common vision defect where a person can see nearby objects clearly but has difficulty seeing distant objects. This occurs when the eyeball is slightly longer than normal or the cornea is too curved, causing light rays to focus in front of the retina instead of on it. As a result, distant objects appear blurry.
6.
With both eyes open, a person’s field of view is about:
Correct Answer
C.
Explanation
With both eyes open, a person's field of view is about 180 degrees horizontally and about 120 degrees vertically. This is because each eye has a field of view of about 90 degrees horizontally, and the fields of view from both eyes overlap, creating a wider overall field of view. The vertical field of view is slightly smaller due to the position and shape of the eye sockets.
7.
The reason for stars appearing higher in sky than they actually are; is because of:
Correct Answer
C. Refraction of light
Explanation
Refraction of light is the correct answer because when light passes through the Earth's atmosphere, it undergoes refraction, which causes the light rays to bend. This bending of light makes the stars appear higher in the sky than they actually are. Refraction occurs due to the variation in the density of the Earth's atmosphere, causing the light to change direction as it passes through different layers. This phenomenon is responsible for the apparent displacement of celestial objects, making them appear higher or lower in the sky than their actual position.
8.
When a beam of white light falls on a glass prism, the colour of light which undergoes the least bending of all is:
Correct Answer
B. Red
Explanation
When a beam of white light passes through a glass prism, it undergoes dispersion, meaning that the different colors of light are separated. This is because different colors of light have different wavelengths and therefore different speeds in the prism. The color that undergoes the least bending is red. This is because red light has a longer wavelength compared to the other colors of light. As a result, red light is refracted the least and deviates the least from its original path.
9.
The sky appears blue because some of the blue component of the sunlight is scattered by:
Correct Answer
A. Gas molecules present in air
Explanation
The sky appears blue because the blue component of sunlight is scattered by gas molecules present in the air. This scattering occurs when the light waves interact with the gas molecules and get redirected in different directions. Since blue light has a shorter wavelength, it is scattered more than other colors, making the sky appear blue. Dust particles, water droplets, and soot particles also scatter light, but they do not play a significant role in the blue color of the sky.
10.
Which of the following figures correctly represents the passage of white light through prism?
Correct Answer
A.
11.
Figure a, b, c respectively; indicate the point in case of:
Correct Answer
C. The normal eye, the hypermetropic eye and myopic eye
Explanation
The correct answer indicates the correct order of the eye conditions in terms of their visual characteristics. The normal eye has normal vision and does not require corrective lenses. The hypermetropic eye is farsighted, meaning it has difficulty seeing objects up close and may require reading glasses. The myopic eye is nearsighted, meaning it has difficulty seeing objects far away and may require distance glasses or contact lenses. Therefore, the correct order is the normal eye, the hypermetropic eye, and the myopic eye.
12.
When a graph is plotted taking angle of deviation along the y axis and angle of incidence along the x axis, which of the following figures correctly represents this variation?
Correct Answer
A.
13.
In which of the following cases will no dispersion take place when sunlight passes through it?
Correct Answer
B.
Explanation
No dispersion will take place when sunlight passes through a medium that has a uniform refractive index for all wavelengths of light. This means that the speed of light is the same for all colors of light as they pass through the medium. When the refractive index is the same for all wavelengths, there is no bending or separation of the different colors of light, resulting in no dispersion.
14.
A: Astigmatism is a focusing error in two perpendicular lines.
B: Stars twinkle due to refraction in the fluctuating atmosphere.
Correct Answer
A. Both 'A' and 'B' are true statements
Explanation
Both statement A and B are true.
Statement A accurately describes astigmatism, which is a refractive error that occurs when the cornea or lens of the eye has an irregular shape, causing blurred or distorted vision in both horizontal and vertical lines.
Statement B is also true, as stars twinkle due to the refraction of their light in the fluctuating atmosphere. When starlight passes through Earth's atmosphere, it encounters variations in temperature, humidity, and density, causing the light to bend and scatter, resulting in the twinkling effect we observe.
15.
Having two eyes facilitates in:
A: Increasing the field of view
B: Bringing a three-dimensional view
C: Developing the concept of distance/size.
Then the correct option is/are:
Correct Answer
D. A, B and C
Explanation
Having two eyes facilitates in increasing the field of view, bringing a three-dimensional view, and developing the concept of distance/size. This is because having two eyes allows for binocular vision, which means that each eye sees a slightly different image. The brain then combines these two images to create a single, three-dimensional perception of the world. Additionally, having two eyes also increases the field of view, as each eye has its own visual field. This allows for a wider range of vision and better detection of objects in the environment. Finally, having two eyes helps in developing the concept of distance and size, as the brain uses the slight differences in the images received by each eye to perceive depth and accurately judge the distance and size of objects.