Follow your curiosity

What discovery has been shared with you?

FACTREE gives you something interesting to discover every day — and something worth talking about together.

Start with one fact. Explore it, go deeper, then follow whichever branch catches your imagination.

Choose subjects for a surprise

Exploring any topic

Begin your discovery

Your next discovery is one click away.

Choose one or more subjects above, or leave Any Topic selected and let curiosity decide.

Physics

Photoelectric Threshold Frequency

Quick fact

The photoelectric effect only occurs if the incoming light has a frequency above the threshold frequency for that material.

Why this is interesting

Have you ever wondered why some lights can power your phone, but others cannot? It all starts with a tiny threshold frequency of light.