Science

Light

Question:

Describe the construction of a kaleidoscope.

Answer:

Construction of a kaleidoscope:Three rectangular mirror strips of dimensions 15cm x 4cm (I X b) are joined together to form a prism. This prism is fixedinto a circular cardboard tube.The circular cardboard tube should be slightly longer that the prism. This circular tube is now closed at one end with a cardboard disc. This disc has a hole in it through which we can see (fig c) At the other end of the circular tube, a plane glass plate is fixed. It is important that this glass plate touches the prism mirrors. On this glass plate, several small and brokenpieces of coloured glass are placed. This end is now closed by a round glass plate allowing enough space for the coloured glass pieces to move .NCERT Solutions for Class 8th Science Chapter 16 Light.
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Questions and Answers

Light

Q 1.

State the laws of reflection.
Answer

Q 2.

What is the angle of incidence of a ray if the reflected ray is at an angle of 90° to the incident ray?
Answer

Q 3.

(a)Find out the position of the image of an object situated at A in the plane mirror (Fig. 16.21).(b)Can Paheli at B see this image?(c)Can Boojho at C see this image?(d)When Paheli moves from B to C, where does the image of A move?
Answer

Q 4.

Gurmit wanted to perform Activity 16.8 using a laser torch. Her teacher advised her not to do so. Can you explain the basis of the teacher's advice?
Answer

Q 5.

Two mirrors meet at right angles. A ray of light is incident on one at an angle of 30° as shown in Fig. 16.19. Draw the reflected ray from the second mirror.
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Q 6.

Boojho stands at A just on the side of a plane mirror as shown in Fig. 16.20. Can he see himself in the mirror? Also can he see the image of objects situated at P. Q and R?
Answer

Q 7.

Differentiate between regular and diffused reflection. Does diffused reflection mean the failure of the laws of reflection?
Answer

Q 8.

Describe the construction of a kaleidoscope.
Answer

Q 9.

Explain how you can take care of your eyes.

Answer

Q 10.

Describe an activity to show that the incident ray, the reflected ray and the normal at the point of incidence lie in the same plane.
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Q 11.

Suppose you are in a dark room. Can you see objects in the room? Can you see objects outside the room? Explain.
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Q 12.

How many images of a candle will be formed if it is placed between two parallel plane mirrors separated by 40 cm?
Answer