Submarines submerged under sea water use an optical instrument containing two plane mirrors angled at…
Submarines submerged under sea water use an optical instrument containing two plane mirrors angled at $45^\circ$ to observe ships on the surface. What is this device?
Kaleidoscope
Microscope
Periscope
Telescope
Solution
A periscope uses two mirrors at $45^\circ$ angles to reflect light rays twice, enabling viewing around obstacles or above water.