Celebrating Science : Activities 3-4



#Science Activity 3: Have you ever wondered what makes certain things glow under Black Lights?

What you will need:

• A Black light 

• Petroleum jelly

• A piece of paper



Instructions:

1. First we will use the petroleum jelly as a kind of invisible ink. 
2. Dip your finger into the jelly, then use your finger to write a message on the piece of paper. 
3. Use more jelly if you need to – but this probably isn’t the time to write a long speech! 
4. When you’re finished, wipe any remaining jelly off your finger. Have the black light ready, then turn off the room lights and turn on the black light.

Can you see the message? Why is something that you couldn’t see in room light now visible when you can’t see any light?


What's happening?

First, let’s talk about the light. The reason black lights are called "black lights" is because they give off very little light that our eyes can see. Visible light contains a spectrum of colors ranging from red, through orange, yellow, green, and blue, to violet or purple. Beyond violet light in the spectrum is ultraviolet light, which our eyes cannot detect.

If we can't see ultraviolet light, why does the petroleum jelly glow under the black light?
Most of the time when we look at an object, we see light reflected from the surface of the object. But with a black light, there isn't much visible light, so simple reflection of light doesn't account for how bright the jelly glows. Petroleum jelly contains substances called phosphors. A phosphor absorbs radiation and emits it as visible light. So the phosphors in the jelly are absorbing the invisible ultraviolet radiation from the black light and emitting visible light.


#Science Activity 4: The Fireproof Balloon!

Balloons are rather fragile things. You know that they must be kept away from sharp objects. The also need to be kept away from flames. A fire can weaken the rubber and cause it to burst. However, in this experiment you will find out how you can hold a balloon directly in a flame without breaking the balloon.

What you will need:

  • Two round balloons, not inflated
  • Several matches
  • Water
Caution: Be careful when handling matches to avoid burning yourself or causing accidental fires.

Instructions:

1. Inflate one of the balloons and tie it closed. 
2. Place 60 milliliters (¼ cup) of water in the other balloon, and then inflate it and tie it shut.
3. Light a match and hold it under the first balloon. Allow the flame to touch the balloon. What happens? The balloon breaks, perhaps even before the flame touches it.
4. Light another match. Hold it directly under the water in the second balloon.
5. Allow the flame to touch the balloon. 

What happens with this balloon? The balloon doesn't break. You may even see a black patch of soot form on the outside of the balloon above the flame.






What's happening?
Balloons are made out of rubber. Rubber heats up really fast so the first balloon pops fast. Water molecules take a long time to heat up. The heat from the candle is soaked up by the water inside the second balloon so that balloon does not pop right away.

Water is a particularly good absorber of heat. It takes a lot of heat to change the temperature of water. It takes ten times as much heat to raise the temperature of 1 gram of water by 1C than it does to raise the temperature of 1 gram of iron by the same amount. This is why it takes so long to bring a teakettle of water to the boil. On the other hand, when water cools, it releases a great deal of heat. This is why areas near oceans or other large bodies of water do not get as cold in winter as areas at the same latitude further inland.


Stay tuned daily for more interesting kids activities this week! Feel free to send in your ideas and comments.

Team Avishkaar Box
+91 8506931515
www.avishkaarbox.com





Celebrating Science : Activities 3-4 Celebrating Science : Activities 3-4 Reviewed by Avishkaar Box on 05:33 Rating: 5

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