LIGHTENED TO LIGHT

  Chapter 13 Fun with Magnets 1.       It was observed that a pencil sharpener gets attracted by both the poles of a magnet although its body is made of plastic. Name a material that might have been used to make some part of it. Ans:   Iron is used to make some part of sharpener due to which it is attracted toward magnet. . 2.       Write any two properties of a magnet. Ans:   Two properties of magnets are: (i) A magnet has two poles: North pole and South pole. (ii) Like poles repel each other and unlike poles attract each other. 3.       Where are poles of a bar magnet located? Ans:  Poles are located at the ends of bar magnet just before the ends. These are north and south poles. 4.       A bar magnet has no markings to indicate its poles. How would you find out near which end is its north pole located? Ans:  Take the bar magnet and sus...

  Chapter 12 Electricity and Circuits 1. What is the purpose of using an electric switch? Name some electrical gadgets that have switches built into them. Ans:  Electric switch is used to make electric circuit open or closed for a particular appliance and hence with the help of a switch we can use an appliance according 2. Would the bulb glow after completing the circuit shown in Fig. 12.9 if instead of safety pin we use an eraser? Ans:  No, since eraser is an insulator so it does not allow the current to pass. Hence the bulb will not glow. 3. Using the“conduction tester” on an object it was found that the bulb begins to glow. Is that object a conductor or an insulator? Explain. Ans:  Yes, if the object is good conductor of electricity then current will pass through conduction tester and the bulb will glow. Hence the object will be a conductor of electricity. 4. Why should an electrician use rubber gloves while repairing an electric switch at your h...

  Chapter 11 Light Shadows and Reflection   1.    In a completely dark room, if you hold up a mirror in front of you, will you see a reflection of yourself in the mirror? Ans:  No, in a completely dark room no image will be formed because there is no light in the room so no reflection of light takes place and no image will be formed. 2.   Whether the moon is luminous or non-luminous body? Ans:  Moon is non-luminous body. 3.   What is umbra? Ans:  Umbra is the dark region behind object facing light which does not receive light at all. 4.   How does a light ray travel? Ans:  Light ray travels in a straight line. 5.   Give one natural source of light.  Ans:  Sun is a natural source of light. 6.   What is shadow?  Ans:  Shadow is the dark space behind an opaque object where light does not reach. 7.   What is penumbra? Ans:  The less darker shadow formed penumbra.on the per...