## 19 October 2011

### 8th science test paper Chapter Light

8th science test paper Chapter Light
CLASS 8TH Physics-Sample Paper-2012
1. Fill in the blanks:
(a) The planet which is farthest from the sun is __
(b) The planet which appears reddish in colour is __
(c) A group of stars that appear to form a pattern in the sky is known as a __ (d) A celestial body that revolves around a planet is known as a
(e) Shooting stars are actually not ----
(f) Asteroids are found between the orbits of ------ and ----
(II) Choose correct one 1x 5= 5
1) A stick in water appears broken due to
(a) Reflection of light (b) refraction of light (c) total internal reflection (d) none of these
2) Refractive index of diamond with respect to vacuum is 2.5, then the velocity of light in diamond is.(a) 25×108 m/s (b)2.5×108m/s (c)1.2×108m/s (d)2.1×108m/s
3) Lateral displacement is directly proportional to:
(a) Angle of incidence (b) angle of refraction(c) Thickness of the slab(d) velocity of light
4) A drop of water appears like pearl due to
(a)refraction (b) none (c)reflection (d) total internal reflection
5) Myopia can be corrected using
(a)concave lens (b)convex lens (c)cylindrical lens (d) Plano convex lens
(II) Answer in brief (any five)
1. Define refractive index. which medium will bend light more- glass or water?
2. What is difference between the displacement produced by a rectangular glass slab in a ray of light and the deviation produced by a glass prism?
3. Explain the term spectrum. Why does a glass prism split white light into its constituent colour?
4. Why does a concave lens always form a virtual image of an object? Draw a diagram to illustrate this.
5. What do you mean by the accommodation of the eye? What gives the eye the power of commodation?
6. Distinguish between myopia and hypermetropia. Draw diagrams top show how these defects can be corrected by using suitable lenses.
7. What do you mean by refraction of light? In which direction will light bend when travelling from an optically rarer to denser medium?
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