There are two types of photoreceptors in the human retina, rods and cones. It has two triangular bases and three rectangular lateral surfaces. With the aim of imbibing skills and hard work among the students, the solutions have been designed. Short Question Question 1 what advice will a doctor give to a student sitting at the back of the classroom who cannot read clearly the letters written on the blackboard draw ray diagram for the correction of this defect Ans. He found white light emerges on the other side of second prism. The lesser the refraction is, the dimmer the star look.
Cones respond to the colour. When the star light refracted by the atmosphere comes more towards us, it appears brighter than when it comes less towards us. Answer 1: Myopia or short-nearsightedness: It is a vision defect in which a person can see nearby objects clearly but cannot see the distant objects clearly beyond a certain point. For point of the Eye It is infinity for normal eye. To see the nearby objects clearly, the ciliary muscles contract making the eye lens thicker.
In such conditions, the person cannot see the objects distinctly and comfortably. Aqueous humour is a transparent gelatinous fluid filled between cornea and eye lens. Answer Planets are much closer to the earth and are seen as extended sources. Explain using diagrams how the defects associated with myopic and hypermetropic eye can be corrected? Therefore, the Sun appears reddish early in the morning. Persistence of Vision : It is the time for which the sensation of an object continue in the eye. Explain using diagrams how the defects associated with myopic and hypermetropic eye can be corrected? Correction of hypermetropia: A hypermetropia eye is corrected by using a convex lens of suitable focal length.
Refraction of light by spherical lens; Image formed by spherical lenses; Lens formula Derivation not required ; Magnification. To take further steps in life, you need a good academic record. This causes eye lens thicker. Water Droplet Act like Prism It refracts and disperses the incident sunlight, then reflects it internally internal reflection and finally refracts it again, when it emerges out of the water droplet. If forms and inverted and real image on a light sensitive surface called the retina. Human Eye and Colourful World Human Eyes: The human eye is one of the most valuable and sensitive sense organs. Answer 4: The blue colour of the sky is due to the scattering of the sunlight by the molecules of the atmosphere.
Due to accommodation we are able to see the nearby as well as the distance object clearly accommodation is the ability of the ciliary muscles to adjust the curvature and thereby the focal length to get Clear View of the objects. Enable us to see nearby object clearly Near point of the Eye It is 25cm for normal eye. Due to this, there is no change in the state of motion of the bucket. Since light does not get reflected from it so its appearance is dark. It is, however, impossible to identify colours while closing the eyes.
Visit to main page or of the page. Formation of rainbow : The water droplets act like small prisms. Revising notes in exam days is on of the best tips recommended by teachers during exam days. This defect differs from hypermetropia in the cause by which it is produced. Presbyopia : It is a kind of defect in human eye which occurs due to ageing. A son account of atmospheric refraction, the path of rays of light coming from the star goes on varying slightly, the apparent position of the star fluctuates and the amount of starlight entering the eye flickers.
Answer The student is suffering from myopia or short-sightedness. This controls the size of pupil. It is also called the near point of the eye. When we look at the sky, the scattered light enters our eyes and this light contains blue light in a larger proportion. Both forces are acting in opposite directions to each other and hence nullify the effect of each other. Decreases the focal length 3. For a young adult with normal vision, the near point is about 25 cm.
The different parts of these planets produce either brighter or dimmer effect in such a way that the average of brighter and dimmer effect is zero. Finally, the eye lens forms a clear image at the retina. Would writing the equations get you extra marks or would you just be wasting your time? If you have any doubts, please comment below. A person is able to see objects clearly only when these are lying at distance between 50 cm and 300 cm from his eye. Increasing in focal length: When the ciliary muscles are relaxed, the lens becomes thin. What happens to the image distance in the eye when we increase the distance of an object from the eye? When we increase the distance of an object from the eye, the image distance in the eye does not change. The molecules in the air scatter blue light more than red light as blue light has shortest wavelength as compared to that of red light which has about 1.
उत्तर- इस अवस्था में विद्यार्थी निकट दृष्टि रोग मायोपिया से पीड़ित है। उसे उचित क्षमता के अवतल लैंस से सुधरा जा सकता है। अभ्यास के प्रश्नों के उत्तर प्रश्न 5. Most of the refraction occurs at the outer surface of the cornea. Relaxation of muscles makes the lens thinner and its focal length increases to make us see the distant objects clearly. The given person will be able to clearly see the object kept at 25 cm near point of the normal eye , if the image of the object is formed at his near point, which is given as 1 m. Apparent Star Position : It is due to atmospheric refraction of starlight. Iris is the coloured part of the eye that controls the amount of light by regulating the pupil size.