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CLASS-6, SCIENCE, LESSON-12, LIGHT, INDEX, 3/1/22-ONLINE EXPLANATION, 8/1/22-BOOK EXERCISES AND QUESTION ANSWER PDF, WRITE THIS WORK IN YOUR NOTEBOOK., Define, a) Mirror—A mirror is a smooth polished surface which reflects the light ., b) Reflection---The phenomenon of bouncing back of light after striking an, opaque surface is called reflection., c) Bioluminescence—Emission of light by organism is called, bioluminescence eg.fire fly, Q1.What is light?, Ans Light is a form of energy which enables us to see., Q 2.What is a luminous object?, Ans An object having its own light is called a luminous object, e.g., torch,, sun, etc.
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Q3. What is a non-luminous body?, Ans An object which does not have its own light is called a non-luminous, object, e.g., chair, moon, etc., Q4.Name four natural luminous bodies., Ans The sun, firefly, stars and fire., Q5 Name some artificial source of light., Ans Candle, bulb, kerosene oil, lamp and torch., Q6. What is a transparent object?, Ans An object which allow light to pass through it, is called transparent, object, e.g., clear glass, water, etc., Q7. What is a translucent object?, Ans An object which allows only a small part of light to pass through it, is, called translucent object, e.g., wax paper, fog, etc., Q8,.What is an opaque object?, Ans An object which does not allow light at all to pass through it, is called, opaque object, e.g., wooden sheet, wall, etc., Q9.Write some characteristics of light., Ans-1.Light is a form of energy which enables us to see the objects around, us., 2.It travels in a straight line., 3. It is the fastest travelling energy. It travels with a speed of 3,00,000, kilometers per second., , Q10. What is a shadow?, Ans The dark patch formed due to obstruction of light rays by an opaque, object is called a shadow., Q11.Define a pinhole camera. On which property of light a pinhole, camera does work?
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Ans A pinhole camera is a device which forms a photograph like image of, a bright object on a screen. It works on the property of Rectilinear, propagation of light., Q12.What is rectilinear propagation of light?, Ans The property due to which light travels in a straight line is called, rectilinear propagation of light., Q13.Why shadows are black in colour?, Ans Shadow is formed by an object by obstructing light so that it doesn’t, reach a surface. The area in shadow appears black because there is no, light falling on it., Q14.What are the essential conditions for formation of shadows?, Ans A shadow is formed when, 1. there is a source of light., 2. there is an opaque object in the way of light., 3. the light ray falling on the opaque object is blocked by it., Q15.Write two differences between a shadow and an image., Ans 1.) A shadow is formed due to the blocking of light by an opaque, object,while the image is formed due to reflection of light from an opaque, smooth and shiny surface, 2) A shadow is always dark while the image shows true colours of the, object., Q16.What is an eclipse? What are the two types of eclipse?, Ans The formation of shadows by celestial bodies on one another is called, an eclipse. There are two types of eclipse., 1. When the moon comes in between the sun and the earth, the shadow, of the moon falls on the earth. This is called solar eclipse., 2. When the earth comes in between the sun and the moon, the shadow, of the earth falls on the moon. This is called lunar eclipse., 3. Draw diagrams given on page 158., CHAPTER COMPLETED
