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Storytime - Balloon Magic

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Physics Volunteer Activities

Read "Curious George and the Hot Air Balloon" and learn about the properties of light.

This workshop consists of two parts: a reading of "Curious George and the Hot Air Balloon" by H. A. Rey and Margret Rey, followed by balloon magic demonstrations!

This storytime virtual outreach activity is split into a pre-activity document - i.e., workshop overview and list of materials with preparation instructions for both the volunteer and educator, and PowerPoint presentation with presenter notes to help lead the workshop virtually.

What You Need

For the reading:

  • "Curious George and the Hot Air Balloon" by H. A. Rey and Margret Rey

For the activity:

  • Black and white balloons
  • Coloured balloons
  • Magnifying glasses
  • Sunlight
  • Stop watch - optional

Pre-Activity Document:

PowerPoint:

Safety Notes

Ensure you are familiar with Let's Talk Science's precautions with respect to safe delivery of virtual outreach to youth. These precautions can be found in the manual for this activity. 

What To Do

Part A: Reading of "Curious George and the Hot Air Balloon" by H. A. Rey and Margret Rey

Part B: Doing the Activity

  • Blow up the clear balloon, but do not tie off the open end.
  • Partially insert the black balloon into the clear balloon. Make sure the opening to the black balloon is still accessible.
  • Blow up the black balloon until it is about half the size of the clear balloon and tie off the black balloon. Once tied off, push the black balloon the rest of the way into the clear balloon and tie off the clear balloon.
  • Use the magnifying glass to focus sunlight on the black balloon inside. The black balloon pops!

Discovery

What's Happening?

When you use a magnifying glass to focus the sun's rays to a focal point, you create a spot that is incredibly hot. Luckily, for the clear balloon, most of the light and its heat pass right through the balloon's surface. You've seen this in action before. When you look through glass windows, a clear drinking cup, or even a pair of glasses, you're witnessing light passing through a surface. Since the clear balloon is nearly transparent, the same thing happens when it is exposed to light, even in a high concentration.

The black balloon is not so lucky. When we're talking about light, black is created by a surface that doesn't reflect any light. Instead it absorbs almost all of it. This "absence" of reflected light creates the black color we perceive. With a surface absorbing all of that light, it also absorbs the energy. In this case, that energy is heat, and a lot of it. The heat absorbed by the black balloon from the focused sunlight quickly causes the bonds of the balloon to weaken until it can no longer contain the air on the inside. The pressure from the air is just too much as it explodes, releasing the air into the clear balloon.

What's Happening?

When you use a magnifying glass to focus the sun's rays to a focal point, you create a spot that is incredibly hot. Luckily, for the clear balloon, most of the light and its heat pass right through the balloon's surface. You've seen this in action before. When you look through glass windows, a clear drinking cup, or even a pair of glasses, you're witnessing light passing through a surface. Since the clear balloon is nearly transparent, the same thing happens when it is exposed to light, even in a high concentration.

The black balloon is not so lucky. When we're talking about light, black is created by a surface that doesn't reflect any light. Instead it absorbs almost all of it. This "absence" of reflected light creates the black color we perceive. With a surface absorbing all of that light, it also absorbs the energy. In this case, that energy is heat, and a lot of it. The heat absorbed by the black balloon from the focused sunlight quickly causes the bonds of the balloon to weaken until it can no longer contain the air on the inside. The pressure from the air is just too much as it explodes, releasing the air into the clear balloon.

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