Why is red light used on submarines?

Asked by: John Awbery, Reading

The human eye is less sensitive to longer wavelengths, so red light is chosen to preserve the night vision of the crew while still allowing them to still see their instrument panels.

Submarines switch to red light when it’s dark outside and crew members need to use the periscope or go on watch duty.

Read more:

• Why does light leave the position from which it is created?
• What causes the Northern Lights?

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