Advertisements
Advertisements
प्रश्न
The muscles of a normal eye are least strained when the eye is focussed on an object
पर्याय
far away from the eye
very close to the eye
at about 25 cm from the eye
at about 1 m from the eye
Advertisements
उत्तर
far away from the eye
A normal eye can see from 25 cm to infinity; it faces least difficulty and strain focussing on the object as far as it could be.
APPEARS IN
संबंधित प्रश्न
A virtual image, we always say, cannot be caught on a screen. Yet when we ‘see’ a virtual image, we are obviously bringing it on to the ‘screen’ (i.e., the retina) of our eye. Is there a contradiction?
For a normal eye, the far point is at infinity and the near point of distinct vision is about 25cm in front of the eye. The cornea of the eye provides a converging power of about 40 dioptres, and the least converging power of the eye-lens behind the cornea is about 20 dioptres. From this rough data estimate the range of accommodation (i.e., the range of converging power of the eye-lens) of a normal eye.
A myopic person has been using spectacles of power −1.0 dioptre for distant vision. During old age, he also needs to use the separate reading glass of power + 2.0 dioptres. Explain what may have happened.
A person looking at a person wearing a shirt with a pattern comprising vertical and horizontal lines is able to see the vertical lines more distinctly than the horizontal ones. What is this defect due to? How is such a defect of vision corrected?
What should be the distance between the object and the magnifying glass if the virtual image of each square in the figure is to have an area of 6.25 mm2. Would you be able to see the squares distinctly with your eyes very close to the magnifier?
In viewing through a magnifying glass, one usually positions one’s eyes very close to the lens. Does angular magnification change if the eye is moved back?
When objects at different distances are seen by the eye, which of the following remain constant?
A person A can clearly see objects between 25 cm and 200 cm. Which of the following may represent the range of clear vision for a person B having muscles stronger than A, but all other parameters of eye identical to that of A?
The focal length of a normal eye-lens is about
The distance of the eye-lens from the retina is x. For a normal eye, the maximum focal length of the eye-lens
A man wearing glasses of focal length +1 m cannot clearly see beyond 1 m
A person looks at different trees in an open space with the following details. Arrange the trees in decreasing order of their apparent sizes.
| Tree | Height(m) | Distance from the eye(m) |
| A | 2.0 | 50 |
| B | 2.5 | 80 |
| C | 1.8 | 70 |
| D | 2.8 | 100 |
Can virtual image be formed on the retina in a seeing process?
A normal eye has retina 2 cm behind the eye-lens. What is the power of the eye-lens when the eye is (a) fully relaxed, (b) most strained?
A myopic adult has a far point at 0.1 m. His power of accomodation is 4 diopters.
- What power lenses are required to see distant objects?
- What is his near point without glasses?
- What is his near point with glasses? (Take the image distance from the lens of the eye to the retina to be 2 cm.)
