JSIERT https://validator.w3.org/feed/docs/rss2.html The change in focal length of an eye-lens is caused by the action of the: (a) pupil (b) retina (c) ciliary muscles (d) iris Home Differentiate between pollen grain and ovule. b. State in brief functions of the following parts of the human female reproductive system. (i) Ovary (ii) Fallopian Tube (iii) Uterus Refraction of light in the eye occurs at: (a) the lens only (b) the cornea only (c) both the cornea and the lens (d) the pupil Can You Really Learn a Full Course for Just ₹1? Find Out Here Name the defect of vision which can be corrected by a diverging lens. Show clearly by a ray diagram how the lens corrects the defects. The least distance of distinct vision for a young adult with normal vision is about: (a) 25m (b) 2.5cm (c) 25cm (d) 2.5m Name the defect of vision which can be corrected by a converging lens. Show clearly by a ray diagram how the lens corrects the defect. Differentiate between myopia and hypermetropia. What type of spectacles should be worn by a person having the defects of myopia as well as hypermetropia? How it help? What are the two most common defects of vision? How are they corrected? Explain with the help of labelled ray diagram, the defect of vision called myopia and how it is corrected by a lens. Name the defect of vision which can be corrected by a diverging lens. Show clearly by a ray diagram how the lens corrects the defects. Name the defect of vision which can be corrected by a converging lens. Show clearly by a ray diagram how the lens corrects the defect. Differentiate between myopia and hypermetropia. What type of spectacles should be worn by a person having the defects of myopia as well as hypermetropia? How it help? Which defect of vision can be rectified: (a) By using a concave lens? (b) By using a convex lens? The human eye possesses the power of accommodation. This is the power to: (a) alter the diameter of the pupil as the intensity of light changes (b) distinguish between lights of different colours (c) focus on objects at different distances (d) decide which of the two objects is closer Name the defect of vision in a person: (a) Whose near point is more than 25cm away. (b) Whose far point is less than infinity. Which of the following controls the amount of light entering the eye? (a) ciliary muscles (b) lens (c) iris (d) cornea The term “accommodation” as applied to the eye, refers to its ability to: (a) control the light intensity falling on the retina. (b) erect the inverted image formed on the retina. (c) vary the focal length of the lens. (d) vary the distance between the lens and retina. To focus the image of a nearby object on the retina of an eye: (a) the distance between eye-lens and retina is increased (b) the distance between eye-lens and retina is decreased (c) the thickness of eye-lens is decreased (d) the thickness of eye-lens is increased Which of the following changes occur when you walk out of bright sunshine into a poorly lit room? (a) the pupil becomes larger (b) the lens becomes thicker (c) the ciliary muscles relaxes (d) the pupil becomes smaller How does the eye change in order to focus on near or distant object? (a) the lens moves in or out (b) the retina moves in or out (c) the lens becomes thicker or thinner (d) the pupil gets larger or smaller Name one of the common defects of vision and the type of lens used to remove it. The size of the pupil of the eye is adjusted by: (a) cornea (b) ciliary muscles (c) optic nerve (d) iris The human eye forms the image of an object at its: (a) cornea (b) iris (c) pupil (d) retina (a) Explain the functions of the following parts of the eye: (a) cornea (b) iris (c) pupil (d) ciliary muscles (e) eye-lens (f) retina (g) optic nerve (b) If you walk from a dark room into sunlight and back again into dark room, how would your pupils alter in size? What makes this happen? (c) Explain why we cannot see our seats first when we enter a darkened cinema hall from bright light but gradually they become visible. (a) What happens to the size of pupil of our eye (i) in dim light (ii) in bright light (b) Name the cells on the retina of an eye which are sensitive to (i) bright light (ii) dim light (iii) sensation of colour. Energy What is an ATP? What are endothermic reaction ? (a) How does the convex eye lens differ from the ordinary convex lens made of glass? (b) List in order the parts of the eye through which light passes to reach the retina. What are rods and cones in the retina of an eye? Why is our night vision relatively poor compared t the night vision of an owl ? There are two types of light-sensitive cells in the human eye: (a) Where are they found? (b) What is each type called? (c) To what is each type of cell sensitive? Describe and explain how a normal eye can see objects lying at various distances clearly. Ciliary muscles of human eye can contract or relax. How does it help in the normal functioning of the eye? A person walking in a dark corridor enters into a brightly lit room: (a) State the effect on the pupil of the eye. (b) How does this affect the amount of light entering the eye? Why does it take some time to see objects in a dim room when you enter the room from bright sunshine outside? What happens to the eye when you enter a darkened cinema hall from bright sunshine? Give reason for your answer. How is the amount of light entering the eye controlled? What change is made in the eye to enable it to focus on objects situated at different distances? Illustrate your answer with the help of diagrams. The eyes of a person are focused (i) On a nearby object (ii) On a distant object, turn by turn. In which case: (a) The focal length of eye-lens will be the maximum? (b) The converging power of eye-lens will be the maximum? What changes take place in the shape of eye-lens: a) When the eye is focused on a near object? b) When the eye is focused on a distant object? Why is a normal eye not able to see clearly the objects placed closer than 25cm? Fill in the following blanks with suitable words: a) Most of the refraction of light rays entering the eye occurs at the outer surface of the ……. b) The part of eye sensitive to light is ………. c) The part of eye which alters the size of the pupil is …………. d) When light is dim, the pupil becomes …………… e) The iris controls the amount of ……… entering the eye. f) The ciliary muscles control the shape of the ……… g) To bring light from a distant object to a focus on the retina of the eye, the convex eye-lens needs to be made ……. h) To bring light from a near object to a focus on the retina of the eye, the convex eye lens needs to be made …… Is Career Amend a Scam? Here’s the Truth You Should Know Give the scientific names of the following parts of the eye: a) Carries signals from an eye to the brain. b) Muscles which change the shape of the eye-lens. c) A hole in the middle of the iris. d) A clear window at the front of the eye. e) Changes shape to focus a picture on the retina Define the term “power of accommodation” of human eye. Name the part of our eyes which helps us to focus near and distant objects in quick succession. What is the range of vision of a normal human eye? One Rupee Classroom – Your Gateway to Affordable Education