periscope

Everyday

A long tube with mirrors at each end that lets you see over or around something, used in submarines and in toys. tree →

In the lessons

In science lessons on light, pupils build a periscope with two mirrors at 45 degrees to show that light reflects. In stories a submarine raises its periscope to look above the sea. Phrases: up periscope, look through a periscope, make a periscope.

Examples

• The captain raised the periscope to look at the ships. tree →
• We made a periscope from a juice carton and two mirrors. tree →
• With a periscope you can see over a wall. tree →
• Light bounces off both mirrors in a periscope. tree →
• He used his periscope to watch the parade over the crowd. tree →
• The periscope rose out of the water. tree →

Note

Countable: a periscope, periscopes. The mirrors are parallel, each tilted at 45 degrees. Do not mix up with telescope (makes far things look nearer) or microscope (makes tiny things look bigger).