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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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We cannot see the thing in the dark room because there is no light which can make things visible.we can see things outside the room because there will be light which will make every things visible outside the room
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What makes things visible to us?why cannot we see a book which is placed
a. behind a wooden screen b. in a dark room |
When the light coming from an object enters our eyes that we see that object makes things visible to us
a. We cannot see the book behind a wooden screen because wood is a non luminous object and cannot emit their own light to make book visible. b.we cannot see it in a dark room because there is no source of light in a dark room so to see an object we need a source of light |
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1. We can see the sun because it is glowing .how are we able to see the moon?
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We can see the moon because moon reflects light received from the sun into our eyes
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1. Name the two types of reflection of light. what type of reflection makes us see an object from all directions
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Regular reflection
diffuse reflection the diffuse reflection makes us see an object from all direction |
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1. A wall reflects light and a mirror also reflects light. what difference is thee in the way they reflect light
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The wall has a rough surface so the diffuse reflection takes plce.in this case the incident ray do not remain parallel after reflection but are scattered in different directions so no image is formed.inmirror the surface is smooth so that when the beam of parallel rays falls on the surface they are reflected as a beam of parallel light rays.this is called regular reflection and hence image is formed
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Explain why a book lying on a table in a room can be seen from all parts of the room
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It is because of the diffuse reflection of light from its surface .the surface of book being rough scatters the incident light in all parts of a room.hence the book can be seen from all parts of the room
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1. What is the full form of <i and <r? what is the relation between them
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<i is angle of incidence
<r is angle of reflection angle of incidence is equal to angle of reflection |
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1. You see your image in a plane mirror? state two characteristics of the image so formed
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yes we see imagein a plane mirror the characteristiv of images are: 1. the image formed is virtual 2. the image formed is erect |
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1. What is a periscope? How many mirrors are there in a periscope
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It is a long tubular device through which a person can see objects that are out of the direct line of sight.there are two plane mirrors in the periscope
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1. State the various uses of periscope
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1. it is used to see over the heads of a crowd like football match
2. it is used by the soldiers sitting in a trench to observe the activiteis of the enemy outside 3. it is used by a navy officer sitting in a submarine to see the ships over the surface of sea |
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1. Explain how a hair dresser makes you see hair at the back of your head after the hair cut is complete
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After cutting the hair the hair dresser holds a small mirror behind the head of the person.the light coming from the hair at the back of the head is reflected by the small mirror on to a big mirror which is in front of the person .the big mirror reflects the reflected light again due to which we see the image of the back hair
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1. How many images of an object will be formed when the object is placed between two plane mirrors which are inclined at the following to one another
a. 120o
b. 45o
c. 180o
d. 60o
e. 90o
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Formula: (360o /x)-1
a. 2 b. 7 c. 1 d. 5 e. 3 |
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1. Two plane mirrors are set at right angles to each other .a coin is placed in between these two plane mirrors .how many images of the coin will be seen
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3
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1. How many images of a candle will be formed if it is placed between two parallel plane mirrors separated by 40 cm
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Infinite number
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1. Explain why, when an object is placed between two plane mirrors inclined at an angle then multiple images are formed
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This is because the image formed in one plane mirror acts as an object for the other plane mirror thus multiple images are formed
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