Light

Samacheer Book Back Questions And Answers For Science Standard 8 “Light“

I. Choose the best answer:
1. Mirrors having a curved reflecting surface are called as _____.
(a) Plane mirrors
(b) Spherical mirrors
(c) Simple mirrors
(d) None of the above

2. The spherical mirror with a reflecting surface curved inward is called _____.
(a) Convex mirror
(b) Concave mirror
(c) Curved mirror
(d) None of the above

3. The spherical mirror used as a rear view mirror in the vehicle is _____.
(a) Concave mirror
(b) Convex mirror
(c) Plane mirror
(d) None of the above

4. The imaginary line passing through the centre of curvature and pole of a spherical mirror is called _____.
(a) Centre of curvature
(b) Pole
(c) principal axis
(d) Radius curvature

5. The distance from the pole to the focus is called _____.
(a) Pole length
(b) Focal length
(c) principal axis
(d) None of the above

6. If the image and object distance is same, then the object is placed at
a) infinity
b) at F
c) between f and P
d) at C

7. If the focal length of a spherical mirror is 10 cm, what is the value of its radius of curvature?
(a) 10 cm
(b) 5 cm
(c) 20 cm
(d) 15 cm

II. Fill in the blanks:
1. The spherical mirror used in a beauty parlour as make – up mirror is _____.
2. Geometric centre of the spherical mirror is _____.
3. Nature of the images formed by a convex mirror is _____.
4. The mirror used by the ophthalmologist to examine the eye is _____.
5. It the angle of incidence is 45°, then the angle of reflection is _____.
6. Two mirrors are parallel to each other, then the number of images formed is _____.

Answers:
1. Concave mirror
2. Pole
3. Smaller, virtual and erect
4. Concave mirror
5. 45°
6. Infinite

III. Match the following:
1. Convex mirror A. Radio telescopes
2. Parobolic mirror B. Rear – view mirror
3. Snell’s law C. Kaleidoscope
4. Dispersion of light D. sin i/sin r =μ
5. Refractive index E. Rainbow

Answers:
1. B
2. A
3. D
4. E
5. C

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