CBSE Book Class 8 Science Activity Lets Make Music

 SOUND

“Well, that's the end of the lesson on sound. I hope everyone has understood the chapter, said Mr. Tarang, the science teacher. I have a wonderful idea to test how well you have understood the lesson, continued Mr. Tarang. Now that you have learnt the properties of sound, create your own musical instrument. Work carefully and try till your instrument can actually make music and not noise. Bring together your musical instruments and let's have a school band. 

“WOW! What a wonderful idea”, shouted the class excitedly in chorus. And they all got into their own groups to discuss their instruments. I am sure you don't want to be left behind, do you? Then join everyone else. Here are some ideas for you.

What to do: 

1.  Tie a large knot at one end of a string about 35cm long.

2.  Make a tiny hole in the middle of the bottom of a paper cup. 

3.  Run the unknotted end of the string through the inside of the cup and poke it through the hole. The knot should prevent the string from going completely through the hole. 

4. Hang it from a hook.

5. Keep the string in stretched state by pulling the cup downward.

6.  Rub your thumbnail down the string, while  pulling the string tightly. 

You will hear a roaring sound. Vibrations in the string make the cup vibrate. The vibrating cup moves the air inside it and makes a louder  sound.  The  same  thing  happens  with  a violin. The vibrating strings make the wooden body vibrate  and  the  inside  air,  thus  making  a  louder sound.  Like  a  guitar,  a  violin  makes  sounds  with vibrating  strings.  Sometimes  a  violin  player  will pluck  the  violin  strings  but  mostly  they'll  make  sound by rubbing the strings with a bow. 

What to do: 

1.  Fill the first bottle almost completely with water. The water level in the second should be a little lower than the first bottle. Continue lowering the level of the water in each successive bottle. 

2.  Gently blow across the top of each bottle until you can make a sound. You will need some practise, 

but do not be disappointed if you don't get it the first time. 

3.  What do you notice about the sounds produced by the bottles?

Please refer to the link below - CBSE Class 8 Science Activity Lets Make Music