Skip to main content

Featured

Black hole

A black hole is a place in space where gravity pulls so much that even light can not get out. The gravity is so strong because matter has been squeezed into a tiny space. This can happen when a star is dying. Because no light can get out, people can't see black holes. They are invisible. Space telescopes with special tools can help find black holes. The special tools can see how stars that are very close to black holes act differently than other stars. How Big Are Black Holes? Blacbe big or small. Scientists think the smallest black holes are as small as just one atom.These black holes are very tiny but have the mass of a large mountain. Mass is the amount of matter, or "stuff," in an object. Another kind of black hole is called "stellar." Its mass can be up to 20 times more than the mass of the sun. There may be many, many stellar mass black holes in Earth's galaxy. Earth's galaxy is called the Milky Way. The largest black holes are called "superma...
Post a Comment
Read more

Invisible ink

 Invisible Ink with Lemon Juice

Making invisible ink is a lot of fun, you can pretend you are a secret agent as you keep all your secret codes and messages hidden from others. All you need is some basic household objects and the hidden power of lemon juice.

What you'll need:


Half a lemon

Water

Spoon

align="left" class="style25 style26" style="font-family: Arial, Helvetica, sans-serif; font-size: 16px;">Bowl

Cotton bud

White paper

Lamp or other light bulb


Instructions:


Squeeze some lemon juice into the bowl and add a few drops of water.

Mix the water and lemon juice with the spoon.

Dip the cotton bud into the mixture and write a message onto the white paper.

Wait for the juice to dry so it becomes completely invisible.

When you are ready to read your secret message or show it to someone else, heat the paper by holding it close to a light bulb.


What's happening?

1

Lemon juice is an organic substance that oxidizes and turns brown when heated. Diluting the lemon juice in water makes it very hard to notice when you apply it the paper, no one will be aware of its presence until it is heated and the secret message is revealed. Other substances which work in the same way include orange juice, honey, milk, onion juice, vinegar and wine. Invisible ink can also be made using chemical reactions or by viewing certain liquids under ultraviolet (UV) light.

 

 

Comments

Post a Comment

Popular Posts