Question 1: Suppose you are in a dark room. Can you see objects in the room? Can you see objects outside the room? Explain.
Answer: It is not possible to see in a dark room because of absence of light. We know that we are able to see something when light falls on it. If there is light outside the room, then the objects outside the room can be seen.
Question 2: Differentiate between regular and diffused reflection. Does diffused reflection mean the failure of the laws of reflection?
Answer: Regular reflection happens from a highly smooth surface, while irregular reflection happens from a rough surface. Clear images are formed in case of regular reflection, while blurred images are formed in case of irregular reflection.
The laws of reflection are followed in every situation. Hence, diffused reflection does not mean the failure of the laws of reflection.
Question 3: Mention against each of the following whether regular or diffused reflection will take place when a beam of light strikes. Justify your answer in each case.
Polished wooden table
Marble floor with water spread over it
Piece of paper
Answer: Regular reflection will only take place in case of a mirror. In other cases, irregular reflection will take place; because the surfaces are not smooth.
Question 4: State the laws of reflection.
Answer: The laws of reflection are as follows:
First Law of Reflection: The incident ray, the reflecting ray and normal at the point of incidence; all lie in the same plane.
Second Law of Reflection: Angle of incidence is always equal to the angle of reflection.
Question 5: 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.
Answer: For this, take a chart paper, a torch and a plain mirror. Paste a black paper on the front of the torch and make a small hole at the centre of black cover. This will give you a thin beam of light.
Question 6: Fill in the blanks:
Answer: (a) 2 m, (b) left, left, (c) more, (d) less number of
Question 7: Angle of incidence is equal to the angle of reflection
Answer: (a) Always
Question 8: Image formed by a plane mirror is
Answer: (b) Virtual, behind the mirror and of the same size as the object
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