Here We provided all 01 Marks Short answer Type Questions Answers of Chapter 6 The Human Eye And The Colourful World of Lakhmir Singh Manjit Kaur Book.
Part 1
(1) What kind of lens is present in the human eye?
Ans. Convex lens is present in human eye.
(2) Name two parts of the eye which refract light rays (or bend light rays).
Ans. Cornea and eye-lens are the two parts of the eye which refract light rays.
(3) Name the part of the eye:
(a) Which controls the amount of light entering the eye.
(b) On which the image is formed
(c) Which changes the focal length of eye – lens.
Ans. (a) Iris controls the amount of light entering the eye.
(b) In Retina image is formed.
(c) Ciliary muscles changes the focal length of eye lens.
(4) What is the name of:
(a) The curved, transparent front surface of the eye?
(b) The light- sensitive layer in the eye?
Ans.(a) Cornea
(b) Retina
(5) Where is the image formed in a human eye?
Ans. At retina image formed in a human eye.
(6) What is the function of the lens in the human eye?
Ans. The functions of humans eye lens that it changes its shape and thickness to focus light on to the retina.
(7) What job does the pupil of the eye do?
Ans. Pupil expands or contracts according to the intensity of light around the eye.
(8) How does the eye adjust to take account of an increase in brightness?
Ans. The pupil of our eye contracts to take account of an increase in brightness.
(9) Name that part of the eye which is equivalent to the photographic film in a camera.
Ans. Retina is the part of the eye which is equivalent to the photographic film in a camera.
(10) Name that part of the retina which is insensitive to light.
Ans. Blind spot is the part of the retina which is insensitive to light.
(11) Which part of the eye contains cells which are sensitive to light?
Ans. Retina contains cells which are sensitive to light.
(12) Name two types of cells in the retina of an eye which respond to light.
Ans. Rods and cones are the two types of cells in the retina of an eye which respond to light.
(13) Out of rods and cones in the retina of your eye:
(a) Which detect color?
(b) Which work in dim light?
Ans. (a) Cones detect color.
(b) Rods work in dim light.
(14) State whether the following statement is true or false:
The image formed on our retina is upside – down.
Ans. True
(15) What is the principal function of the eye – lens?
Ans. Focus light on to the retina is the principal function of the eye – lens.
(16) Where does the greatest degree of refraction of light occur in the eye?
Ans. At cornea the greatest degree of refraction of light occur in the eye.
(17) What changes the shape of lens in the eye?
Ans. Ciliary muscles changes the shape of lens in the eye.
(18) What do the ciliary muscles do when you are focusing on a nearby object?
Ans. The ciliary muscles make the eyes lens more converging.
(19) What is the least distance of distinct vision for a normal human eye?
Ans. 25 cm (Tentative).
(20) What is the:
(a) Far point of a normal human eye?
(b) Near point of a normal human eye?
Ans. (a) The far point of a normal human eye is at infinity.
(b) The near point of a normal human eye is at 25 cm from the eye.
(21) What is the range of vision of a normal human eye?
Ans. Range of vision of a normal human eyes is from infinity to about 25cm.
(22) Name the part of our eyes which helps us to focus near and distinct objects in quick succession.
Ans. Ciliary muscles helps us to focus near and distinct objects in quick succession.
(23) Define the term “power of accommodation” of human eye.
Ans. The ability of an eye to focus the distant objects as well as the nearby objects on the retina by changing the focal length of its lens is called the power of accommodation.
(23) 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 the shape to focus a picture on the retina
Ans. (a) Optic nerve carries signals from an eye to the brain.
(b) Ciliary muscles change the shape of the eye – lens.
(c) Pupil is the hole in the middle of the iris.
(d) Cornea
(e) Eye lens changes the shape to focus a picture on the retina.
(24) 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 of 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 ______
Ans. (a) cornea
(b) retina
(c) iris
(d) large
(e) light
(f) eye-lens
(g) thinner
(h) thicker
Part 2
(1) Name one of the common defects of vision and the type of lens used to remove it.
Ans. One of the common defects of vision is Myopia. Concave lens is used to remove it.
(2) Name the defect of vision in a person:
(a) Whose near point is more than 25 cm away.
(b) Whose far point is less than infinity.
Ans. (a) Hypermetropia is more than 25 cm away.
(b) Myopia, whose far point is less than infinity.
(3) Which defect of vision can be rectified:
(a) by using a concave lens?
(b) by using a convex lens ?
Ans. (a) Myopia using a concave lens.
(b) Hypermetropia using a convex lens.
(4) What type of lens is used to correct (a) hypermetropia (b) myopia?
Ans. (a) Convex lens is used to correct hypermetropia.
(b) Concave lens is used to correct myopia.
(5) What is the other name for (a) myopia (b) hypermetropia?
Ans. (A) Near Sightedness is the other name for myopia.
(B) Far Sightedness is the other name for hypermetropia.
(6) What is the scientific name of (a) short-sightedness, and (b) long-sightedness?
Ans. (a) Myopia is the scientific name of short sightness.
(b) Hypermetropia is the scientific name of long sightedness.
(7) What kind of lens is used to correct (a) short-sightedness (b) long-sightedness?
Ans. (a) Concave lens is used to correct short sightedness.
(b) Convex lens is used to correct long sightedness.
(8) State whether the following statement is true or false:
Short-sightedness can be cured by using a concave lens.
Ans. True
(9) Name the defect of vision in which the eye-lens loses its power of accommodation due to old age.
Ans. Presbyopia is the defect of vision in which the eye-lens loses its power of accommodation due to old age.
(10) Name the defect of vision which makes the eye-lens cloudy resulting in blurred vision.
Ans. Cataract is the defect of vision which makes the eye-lens cloudy resulting in blurred vision.
(11) What is the other name of old age hypermetropia?
Ans. Presbyopia is the other name of old age hypermetropia.
(12) Name any two defects of vision which can be corrected by using spectacles.
Ans. Two defects of vision which can be corrected by using spectacles – Myopia & Hypermetropia.
(13) Name one defect of vision (or eye) which cannot be corrected by any type of spectacle lenses.
Ans. Cataract cannot be corrected by any type of spectacle lenses.
(14) Name the body part with which the terms myopia and hypermetropia are connected.
Ans. Eye is that body part with which the terms myopia and hypermetropia are connected.
(15) What is the far point of a person suffering from myopia (or short-sightedness)?
Ans. Less than infinity is the far point of a person suffering from myopia (or short-sightedness).
(16) Where is the near point of a person suffering from hypermetropia (or long-sightedness?
Ans. The near point of a person suffering from hypermetropia is farther away from the normal near point (25 cm).
(17) Your friend can read a book perfectly well but cannot read the writing on blackboard unless she sits on the front row in class.
(a) Is she short-sighted or long-sighted?
(b) What type of lenses-converging or diverging-would an optician prescribe for her?
Ans.
(a) She is Short-sighted.
(b) Diverging lenses would an optician prescribe for her.
(18) A man can read the number of a distant bus clearly but he finds difficulty in reading a book.
(a) From which defect of the eye is he suffering?
(b) What type of spectacle lens should he use to correct the defect
Ans. (a) Hypermetropia (Long Sightedness)
(b) Convex lens should he use to correct the defect.
(19) A student sitting in the last row of the class room is not able to read clearly the writing on the blackboard.
(a) Name the type of defect he is suffering from.
(b) How can this defect by corrected?
Ans. (a) He is suffering from – Myopia (Short – Sightedness)
(b) By using Concave lens this defect can be correct.
(20) Complete the following sentences:
(a) A short-sighted person cannot see ______ objects clearly. Short-sightedness can be corrected by using ______ lenses.
(b) A long sighted person cannot see _______ objects clearly. Long-sightedness can be corrected by using ______ lenses.
Ans. (a) distant, concave
(b) nearby, convex
Part 3
(1) How much is our field of view:
(a) with one eye open?
(b) with both eyes open?
Ans. (a) About 150 degree
(b) About 180degree
(2) Which of the following will have a wider field of view?
(a) Animals having two eyes on the opposite sides of their head.
(b) Animals having two eyes at the front of their head.
Ans. Animals having two eyes on the opposite sides of their head will have a wider field of view.
(3) Out of animals of prey and predators, which have their eyes:
(i) at the front of their head?
(ii) on the opposite sides of their head?
Ans. (i) Predators
(ii) Animals of prey
(4) State whether the following statement is true or false: Rabbit has eyes which look sideways.
Ans. True
(5) Fill in the following blanks with suitable words:
(a) Having two eyes gives a _________ field of view.
(b) Having two eyes enables us to judge ________ more accurately.
Ans. (a) wider
(b) distances
Part 4
(1) As light rays pass from air into a glass prism, are they refracted towards or away from the normal?
Ans. Towards the normal.
(2) As light rays emerge from a glass prism into air, are they refracted towards or away from the normal?
Ans. Away from the normal.
(3) Name a natural phenomenon which is caused by the dispersion of sunlight in the sky.
Ans. Rainbow is a natural phenomenon which is caused by the dispersion of sunlight in the sky.
(4) What information do we get about sunlight from the formation of a rainbow?
Ans. The info do we get about sunlight from the formation of a rainbow that sunlight consists of seven colors.
(5) What did Newton demonstrate by his experiments with the prism?
Ans. Newton demonstrated by his experiments with the prisms that white light consists of a mixture of seven colours.
(6) What colors make up white light?
Ans. Seven colours are Violet, indigo, blue, green, yellow, orange, red.
(7) Give the meaning of the term VIBGYOR. With which phenomenon is it connected?
Ans. The seven colours of the spectrum of white light are denited by the word VIBGYOR where V stands for Violet, I for Indigo, B for Blue, G for Green, Y for Yellow, O for Orange and R for Red.
It is connected with the phenomenon of dispersion of light.
(8) In the formation of spectrum of white light by a prism:
(i) which colour is deviated least?
(ii) which colour is deviated most?
Ans. (i) Red color is deviated least.
(ii) Violet color is deviated most.
(9) What colours lie on the two sides of the green colour’ in the spectrum of white light?
Ans. Yellow and Blue colours lie on the two sides of the green colour’ in the spectrum of white light.
(10) Name the scientist who discovered that sunlight consists of seven colours.
Ans. Newton discovered that sunlight consists of seven colours.
(11) What is the order of colours in a rainbow, from the outside to the inside ?
Ans. Red, Orange, Yellow, Green, Blue, Indigo and Violet
(12) Which colour of the spectrum has (a) longest wavelength, and (b) shortest wavelength?
Ans. (a) longest wavelength —- Red.
(b) Shortest wavelength —– Violet.
(13) Which light has the longer wavelength: red light or blue light?
Ans. Red Light has the longer wavelength.
(14) Which colour of light has the shorter wavelength- red or violet?
Ans. Violet color of light has the shorter wavelength.
(15) Fill in the blanks with suitable words:
(a) When a ray of light enters a prism, it bends the normal; as it leaves the prism, it bends the normal.
(b) White light is composed of ……….colours. The colours of white light deviated through the largest angle by a prism is ………
Ans. (a) towards, away from
(b) seven, violet
Part 5
(1) Name the phenomenon which causes the twinkling of stars.
Ans. Atmospheric refraction of light causes the twinkling of stars.
(2) Name two effects produced by the atmospheric refraction.
Ans. Two effects produced by the atmospheric refraction : Twinkling of stars; Advance sunrise and delayed sunset.
(3) Which phenomenon makes us see the sun:
(a) a few minutes before actual sunrise?
(b) a few minutes after actual sunset?
Ans. (a) Atmospheric refraction of sunlight.
(b) Atmospheric refraction of sunlight.
(4) Atmospheric refraction causes advance sunrise and delayed sunset. By how much time is:
(a) sunrise advanced?
(b) sunset delayed?
Ans. (a) About 2 minutes.
(b) About 2 minutes.
(5) State whether the following statement is true or false: The planets twinkle at night due to atmospheric refraction of light.
Ans. False
(6) Name the phenomenon due to which the stars seem higher in the sky than they actually are.
Ans. Atmospheric refraction of light
(7) Fill in the following blanks with suitable words:
We can see the sun about ____ minutes before the actual sunrise and about ___minutes after the actual sunset because of atmospheric ____
Ans. Two, Two, Refraction.
Part 6
(1) What is the colour of the sunlight:
(a) Scattered by the dust particles in the atmosphere?
(b) Scattered by the air molecules in the atmosphere?
Ans. (a) White
(b) Blue
(2) Which of the two is scattered more easily: light of shorter wavelengths or light of longer wavelengths?
Ans. Light of shorter wavelengths is scattered more easily.
(3) State whether the following statements are true or false:
(a) The scattering away of red light makes the sky appear blue during the day time.
(b) The scattering away of blue light makes the sun appear red at sunset.
Ans. (a) False
(b) True
(4) What colour does the sky appear to an astraunaut?
Ans. Dark or black.
(5) Which effect is illustrated by the observation that when a beam of sunlight enters a dusty room, then its path becomes visible to us.
Ans. Tyndall effect is illustrated by the observation that when a beam of sunlight enters a dusty room, then its path becomes visible to us.
(6) State two effects produced by the scattering of light by the atmosphere.
Ans. Two effects produced by the scattering of light by the atmosphere are:
(i) Sky appears blue.
(ii) Sun appears red at sunrise and sunset.