Inflate a balloon in a bottle!

Inflate a balloon in a bottle!

At first, a glass bottle and a balloon are required.

Hot water or hot tea is poured into a bottle as shown in a photo.

Just after the pouring, you should cover the entrance of the bottle with the balloon, immediately.

Wait for a hour or so.

Air in the bottle is cooled and you'll find that the bottle is negative  pressure.

Look at the bottle as shown in here.

The balloon was inflated in the bottle!

Hot water or tea may be dangerous for children.

Please take care if you try the exam with your kids.

Let's make a bone conduction headphone!

Let's make a speaker to understand why we can listen to music.

First, you should make a coil. 

The coil is made of copper because you have to flow current to it.

Next, the coil is connected to a component stereo as shown here.

Third, put the coil on the magnet, and adjust the volume.

You can observe that the coil is dancing.

Put the coil and magnet on a can or plastic trash box,  and etc.

You can listen to the music!

This is a hand-made speaker.

Lastly, let's try to listen through bone conduction.

If air vibrates, this is a speaker.

On the other hand, if bone vibrates, this is a bone conduction headphone.

Hope you and your kids enjoy the exam.

Let's ice with salt

Let's ice with salt!

It's easy to play.

First, you should have a thermometer and a lot of ice.

Measure the temperature when the cooling starts. 

After about ten minutes later, the temperature may be stable.

Let's pour three spoons of salt in the ice!

You can observe that the temperature cools more.

 Look at the thermometer!
The temperature falls to -19 degree.

Let's observe the following graph.

You and your kids can understand that Salt is fantastic catalyst.

Hope you and your kids enjoy the exam.