Bell-jar experiment demonstrates that sound needs a medium for its propagation. Take an electric bell and an airtight glass bell jar connected to a vacuum pump. Suspend the bell inside the jar, and press the switch of the bell. You will be able to hear the bell ring.

When that pebble is dropped in the pond, it pushes water out of the way. The water has nowhere to go but to the side and up, creating a circular peak around the drop point. So a ripple spreads out from the drop point even though the individual water molecules are mostly just moving up and down in place.

The experiment is done by placing an electrical bell in the bell jar. As the air is pumped out of the sealed bell jar, the sound from the bell jar fades. At a particular vacuum, no more sound is heard from the bell, but we can see that the hammer continues hitting the gong and sound is produced.

(iii) When the air is removed completely, we will not be able to hear the sound of the bell. Conclusion : This experiment shows that sound requires a medium for its propagation.

To remove water vapor from compressed air, both adsorption (desiccant dryers) and refrigeration (refrigerated dryers) can be used in for different applications and different conditions. A desiccant or adsorption dryer uses desiccant material to adsorb and remove the humidity from compressed air.

For starters, sound travels through water five times faster than it travels through air. But when you’re under water, the sound travels so fast that it reaches both ears at almost the same time. That’s why it was hard to tell where your friend was clinking the underwater spoons.

Sound waves in air (and any fluid medium) are longitudinal waves because particles of the medium through which the sound is transported vibrate parallel to the direction that the sound wave moves.