Exercise
A. Answer the following in not more than 20 words.
1. What happens to the rays of light in case of diffuse reflection?
2. An object is placed 10 cm in front of a plane mirror. Where is the image formed? How far from the mirror?
3. An object is placed between two mirrors that are at right angles to each other. How many images are formed?
4. What is white light? Give an example.
5. Define dispersion.
6. Which parts of the eye make up its converging lens system?
7. A person has myopia. What problem does he face?
8. What is the first stage of nutritional blindness?
B. Answer the following in not more than 40 words.
1. A shiny metal utensil forms an image, but the image is not as clear as that formed by a mirror. Why?
2. State the laws of reflection of light.
3. Write the properties of the image formed by a plane mirror.
4. What is lateral inversion?
5. A book is placed between two mirrors that are at right angles to each other. One of the images formed does not show lateral inversion. Where is this image formed and why is it not laterally inverted?
6. How is the light entering the eye controlled?
7. What do you understand by the blind spot of the eye?
8. What is accommodation? How is it achieved in the human eye?
9. What is Braille?
C. Answer the following in not more than 100 words.
1. How will you prove the first law of reflection of light with the help of a ray box?
2. Describe the structure of the eye with the help of a diagram
3. What vision - related problems occur when the diet lacks vitamin A?
D. Complete the following
1. In regular reflection, the reflected rays remain to each other.
2 The kaleidoscope is a device that uses to produce patterns.
3. The coloured, disc-shaped diaphragm in the eye is called the
4. A person suffering from cannot see nearby objects clearly.
5. The leading cause of blindness is
6. The set of colours formed on splitting of white light is called the of white light
E. Choose the correct option(s). More than one option might be correct.
1. Reflection from an irregular surface
(a) forms a sharp image
(b) is diffuse reflection
(e) forms a hazy image
(d) reflects light in different directions
2. In reflection of light, the angle of incidence)
(a) is the angle between the incident ray and the reflecting surface
(b) is the angle between the incident ray and the normal at the point of incidence
(c) is greater than the angle of reflection
(d) is equal to the angle of reflection
3. In multiple reflections from two plane mirrors
(a) the number of images increases as the angle between the mirrors is increased
(b) the number of images decreases as the angle between the mirrors is increased
(c) the number of images is zero when the angle between the mirrors is zero
(d) the number of images is infinite when the angle between the mirrors is zero
4. The Iris
(a) controls the lens of the eye
(b) controls the amount of light entering the
(c) acts as a converging lens
(d) is controlled by the ciliary muscles
F. Below each item in the first column write the letters from the other two columns to match
1. Dispersion of light
2. Image formed in the eye
3. Image formed by a plane mirror
A Reflection
B. Refraction
m. Is formed on the retina
n. Is laterally inverted
o. Light is split into its component
p. Is of the same size as the object
q. Is very small
r. Is upside down
Answer
A.
1. Light scatters in different directions.
2. Image is formed behind the mirror, at a distance of 10 cm from it.
3. 4 images are formed.
4. White light is a combination of all visible colors. Example: Sunlight.
5. Dispersion is the splitting of white light into its constituent colors.
B.
1. The utensil has imperfections that cause a blurry image.
2. (i) The incident ray, reflected ray, and normal all lie in the same plane. (ii) The angle of incidence is equal to the angle of reflection.
3. Virtual, upright, and of the same size as the object.
4. Lateral inversion is the reversal of left and right in an image.
5. One image is formed at the intersection of the mirrors, and it is not laterally inverted because it is formed by direct reflection.
6. Light entering the eye is controlled by the pupil.
7. Blind spot is the region on the retina where the optic nerve exits, and it lacks photoreceptor cells.
8. Accommodation is the ability of the eye to change its focus from distant to near objects. It is achieved by the ciliary muscles that adjust the curvature of the lens.
9. Braille is a writing system that uses raised dots to represent letters and numbers.
C.
1. Place a plane mirror on a sheet of paper with its straight edge along the paper's edge. Draw a normal to the mirror at its midpoint. Shine a ray of light from a ray box on the mirror. Measure the angle of incidence and the angle of reflection. The two angles are equal, proving the first law of reflection.
2. The eye has a transparent, curved cornea that focuses light onto the lens. The lens further focuses the light onto the retina at the back of the eye. The retina has photoreceptor cells that convert light into electrical signals that are transmitted to the brain via the optic nerve.
3. Vitamin A deficiency can cause night blindness and xerophthalmia, a condition where the cornea becomes dry and opaque, leading to blindness.
D.
1. Parallel.
2. Mirrors.
3. Iris.
4. Myopia.
5. Cataract.
6. Spectrum.
E.
1. (b) is diffuse reflection, (d) reflects light in different directions.
2. (b) is the angle between the incident ray and the normal at the point of incidence, (d) is equal to the angle of reflection.
3. (b) the number of images decreases as the angle between the mirrors is increased.
4. (b) controls the amount of light entering the eye, (d) is controlled by the ciliary muscles.
F.
1. O
2. M
3. PA.
1. Light scatters in different directions.
2. Image is formed behind the mirror, at a distance of 10 cm from it.
3. 4 images are formed.
4. White light is a combination of all visible colors. Example: Sunlight.
5. Dispersion is the splitting of white light into its constituent colors.
B.
1. The utensil has imperfections that cause a blurry image.
2. (i) The incident ray, reflected ray, and normal all lie in the same plane. (ii) The angle of incidence is equal to the angle of reflection.
3. Virtual, upright, and of the same size as the object.
4. Lateral inversion is the reversal of left and right in an image.
5. One image is formed at the intersection of the mirrors, and it is not laterally inverted because it is formed by direct reflection.
6. Light entering the eye is controlled by the pupil.
7. Blind spot is the region on the retina where the optic nerve exits, and it lacks photoreceptor cells.
8. Accommodation is the ability of the eye to change its focus from distant to near objects. It is achieved by the ciliary muscles that adjust the curvature of the lens.
9. Braille is a writing system that uses raised dots to represent letters and numbers.
C.
1. Place a plane mirror on a sheet of paper with its straight edge along the paper's edge. Draw a normal to the mirror at its midpoint. Shine a ray of light from a ray box on the mirror. Measure the angle of incidence and the angle of reflection. The two angles are equal, proving the first law of reflection.
2. The eye has a transparent, curved cornea that focuses light onto the lens. The lens further focuses the light onto the retina at the back of the eye. The retina has photoreceptor cells that convert light into electrical signals that are transmitted to the brain via the optic nerve.
3. Vitamin A deficiency can cause night blindness and xerophthalmia, a condition where the cornea becomes dry and opaque, leading to blindness.
D.
1. Parallel.
2. Mirrors.
3. Iris.
4. Myopia.
5. Cataract.
6. Spectrum.
E.
1. (b) is diffuse reflection, (d) reflects light in different directions.
2. (b) is the angle between the incident ray and the normal at the point of incidence, (d) is equal to the angle of reflection.
3. (b) the number of images decreases as the angle between the mirrors is increased.
4. (b) controls the amount of light entering the eye, (d) is controlled by the ciliary muscles.
F.
1. O
2. M
3. P
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