Write a secret message

In this activity, students use a UV light-emitting diode pen to write secret messages and investigate a range of objects to see if or how they fluoresce.

UV fluorescence

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Information can be kept secret using invisible fluorescent ink that can only be seen under UV light.

Rights: The University of Waikato Te Whare Wānanga o Waikato

By the end of this activity, students should be able to:

• explain why an invisible dye fluoresces when UVA shines on it

• use UV light to investigate objects to see if and how they fluoresce.

Download the Word file (see link below) for:

• introduction/background notes

• what you need

• what to do.