Flashing envelopes

This is an interesting effect best observed in low light (or better yet, utter darkness!)

You will need:

• a self-adhering envelope
• scissors or a letter opener
• a dark place

How to do it:

1. Remove the tab on the envelope and adhere the sticky layers to seal the envelope.
2. Carefully slit open the top of the envelope so that the flap is detached (but still stuck down!).
3. Go to a dark place and quickly pull the flap off the envelope so that the sticky parts unstick. Did you see a flash of bluish light?

What’s happening?

You’ve just seen a phenomenon called triboluminescence, light that is created by mechanical energy. When you pull off the flap, you peel apart many strands of sticky glue. Electrons within the glue are excited (they gain energy) and quickly de-excite (they lose the energy to become more stable). As they de-excite, the energy is emitted as light.

‘Luminescence’ refers to light that is not generated by heat. There are many types of luminescence in nature, including bioluminescence, where organisms make light from chemical reactions. Glow worms, fireflies, glowing bacteria and glowing fungi all use bioluminescence.

You can experience phosphorescence, another form of luminescent light in the Frozen Shadows exhibit at Wonderworks.

Flashing envelopes
Will you see the light?

Explore More

Frozen Shadows
Use phosphorescence in your favour—strike a pose in front of this special wall and a flash of light will cause your shadow to freeze behind you.

See more exhibits...

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