Activity 13.7 Class 8 Science Chapter 13 Solution

Activity 13.7 Class 8 Science Chapter Sound

In this post, you will find NCERT Science Class 8 Chapter 13 activity 13.7 and after reading this, you can understand the meaning of sound, characteristics of sound, propagation of sound, properties of sound, and types of sound waves. You should also go through activity 13.6 of chapter 13.

Activity

 

   ·     Take a metal or glass tumbler.

   ·     Make  sure that it is dry.

   ·     Place a cell phone in it. (Remember that the cell phone must not be kept in water.)

   ·    Ask your friend to give ring on this cell phone from another cell phone.

   ·     Listen to the ring carefully.

   ·     Now, surround the rim of the tumbler with your hand.

   ·     Put your mouth on the opening between your hands.

   ·     Indicate to your friend to give a ring again.

   ·      Listen to the ring while sucking air from the tumbler.

   ·     Does the sound become fainter as you suck air?

   ·     Remove the tumbler from your mouth.

   ·     Does the sound become loud again?

·   

Observation and explanation

When we place a cell phone in a dry tumbler and give it a ring, we can hear a ringing sound because there is air in the tumbler.

Now, we suck all the air from the tumbler and give a ring, this time we hear a faint sound. As we keep sucking the air, the sound becomes fainter and fainter.

When the air is completely sucked from the tumbler, we can’t hear any sound.

 

Conclusion

Activity 13.7 class 8 science shows that sound needs a medium to travel.

 Related Topics

1. Activity 13.8

2. Activity 13.6